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| ff48f2b3a0 | |||
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@ -1,4 +1,4 @@
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||||
[/
|
||||
[/
|
||||
Boost.Optional
|
||||
|
||||
Copyright (c) 2003-2007 Fernando Luis Cacciola Carballal
|
||||
@ -58,7 +58,7 @@ The observation made in the last paragraph about the irrelevant nature of the
|
||||
additional `nil_t` with respect to [_purpose] of `optional<T>` suggests an
|
||||
alternative model: a ['container] that either has a value of `T` or nothing.
|
||||
|
||||
As of this writing I don't know of any precedence for a variable-size
|
||||
As of this writing I don't know of any precedent for a variable-size
|
||||
fixed-capacity (of 1) stack-based container model for optional values, yet I
|
||||
believe this is the consequence of the lack of practical implementations of
|
||||
such a container rather than an inherent shortcoming of the container model.
|
||||
@ -176,14 +176,14 @@ untitialized optional objects: The operators * and ->]
|
||||
A relevant feature of a pointer is that it can have a [*null pointer value].
|
||||
This is a ['special] value which is used to indicate that the pointer is not
|
||||
referring to any object at all. In other words, null pointer values convey
|
||||
the notion of inexistent objects.
|
||||
the notion of nonexistent objects.
|
||||
|
||||
This meaning of the null pointer value allowed pointers to became a ['de
|
||||
facto] standard for handling optional objects because all you have to do
|
||||
to refer to a value which you don't really have is to use a null pointer
|
||||
value of the appropriate type. Pointers have been used for decades—from
|
||||
the days of C APIs to modern C++ libraries—to ['refer] to optional (that is,
|
||||
possibly inexistent) objects; particularly as optional arguments to a
|
||||
possibly nonexistent) objects; particularly as optional arguments to a
|
||||
function, but also quite often as optional data members.
|
||||
|
||||
The possible presence of a null pointer value makes the operations that
|
||||
|
||||
@ -35,12 +35,12 @@
|
||||
optional<string> name ;
|
||||
if ( database.open() )
|
||||
{
|
||||
name.reset ( database.lookup(employer_name) ) ;
|
||||
name = database.lookup(employer_name) ;
|
||||
}
|
||||
else
|
||||
{
|
||||
if ( can_ask_user )
|
||||
name.reset ( user.ask(employer_name) ) ;
|
||||
name = user.ask(employer_name) ;
|
||||
}
|
||||
|
||||
if ( name )
|
||||
@ -63,7 +63,7 @@
|
||||
void clip_in_rect ( rect const& rect )
|
||||
{
|
||||
....
|
||||
m_clipping_rect.reset ( rect ) ; // initialized here.
|
||||
m_clipping_rect = rect ; // initialized here.
|
||||
}
|
||||
|
||||
void draw ( canvas& cvs )
|
||||
|
||||
@ -1,11 +1,11 @@
|
||||
<html>
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=US-ASCII">
|
||||
<title>A note about optional<bool></title>
|
||||
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<meta name="generator" content="DocBook XSL Stylesheets V1.75.2">
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<link rel="next" href="exception_safety_guarantees.html" title="Exception Safety Guarantees">
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||||
</head>
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||||
@ -13,16 +13,16 @@
|
||||
<table cellpadding="2" width="100%"><tr>
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<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../boost.png"></td>
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</div>
|
||||
<div class="section" title="A note about optional<bool>">
|
||||
<div class="section boost_optional_a_note_about_optional_bool_">
|
||||
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
|
||||
<a name="boost_optional.a_note_about_optional_bool_"></a><a class="link" href="a_note_about_optional_bool_.html" title="A note about optional<bool>">A note about
|
||||
optional<bool></a>
|
||||
@ -54,11 +54,11 @@
|
||||
<span class="special">{</span>
|
||||
<span class="identifier">optional</span><span class="special"><</span><span class="keyword">bool</span><span class="special">></span> <span class="identifier">v</span> <span class="special">=</span> <span class="keyword">try</span><span class="special">();</span>
|
||||
|
||||
<span class="comment">// The following intended to pass the value of 'v' to foo():
|
||||
</span> <span class="identifier">foo</span><span class="special">(</span><span class="identifier">v</span><span class="special">);</span>
|
||||
<span class="comment">// But instead, the initialization state is passed
|
||||
</span> <span class="comment">// due to a typo: it should have been foo(*v).
|
||||
</span><span class="special">}</span>
|
||||
<span class="comment">// The following intended to pass the value of 'v' to foo():</span>
|
||||
<span class="identifier">foo</span><span class="special">(</span><span class="identifier">v</span><span class="special">);</span>
|
||||
<span class="comment">// But instead, the initialization state is passed</span>
|
||||
<span class="comment">// due to a typo: it should have been foo(*v).</span>
|
||||
<span class="special">}</span>
|
||||
</pre>
|
||||
<p>
|
||||
The only implicit conversion is to <code class="computeroutput"><span class="keyword">bool</span></code>,
|
||||
@ -70,7 +70,7 @@
|
||||
</div>
|
||||
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
|
||||
<td align="left"></td>
|
||||
<td align="right"><div class="copyright-footer">Copyright <EFBFBD> 2003 -2007 Fernando Luis Cacciola Carballal<p>
|
||||
<td align="right"><div class="copyright-footer">Copyright © 2003-2007 Fernando Luis Cacciola Carballal<p>
|
||||
Distributed under the Boost Software License, Version 1.0. (See accompanying
|
||||
file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
|
||||
</p>
|
||||
@ -78,7 +78,7 @@
|
||||
</tr></table>
|
||||
<hr>
|
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<div class="spirit-nav">
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<a accesskey="p" href="in_place_factories.html"><img src="../../../../../doc/html/images/prev.png" alt="Prev"></a><a accesskey="u" href="../index.html"><img src="../../../../../doc/html/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../../../doc/html/images/home.png" alt="Home"></a><a accesskey="n" href="exception_safety_guarantees.html"><img src="../../../../../doc/html/images/next.png" alt="Next"></a>
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<a accesskey="p" href="in_place_factories.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../index.html"><img src="../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="exception_safety_guarantees.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a>
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</div>
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</body>
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</html>
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@ -1,117 +1,117 @@
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<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
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<title>Acknowledgments</title>
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<link rel="stylesheet" href="../boostbook.css" type="text/css">
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<meta name="generator" content="DocBook XSL Stylesheets V1.75.2">
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<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
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<table cellpadding="2" width="100%"><tr>
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<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../boost.png"></td>
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<td align="center"><a href="../../../../../index.html">Home</a></td>
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<td align="center"><a href="../../../../libraries.htm">Libraries</a></td>
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<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td>
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<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td>
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<td align="center"><a href="../../../../../more/index.htm">More</a></td>
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</div>
|
||||
<div class="section" title="Acknowledgments">
|
||||
<div class="section boost_optional_acknowledgments">
|
||||
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
|
||||
<a name="boost_optional.acknowledgments"></a><a class="link" href="acknowledgments.html" title="Acknowledgments">Acknowledgments</a>
|
||||
</h2></div></div></div>
|
||||
<a name="boost_optional.acknowledgments.pre_formal_review"></a><h4>
|
||||
<a name="id583998"></a>
|
||||
<a class="link" href="acknowledgments.html#boost_optional.acknowledgments.pre_formal_review">Pre-formal
|
||||
<h4>
|
||||
<a name="boost_optional.acknowledgments.h0"></a>
|
||||
<span class="phrase"><a name="boost_optional.acknowledgments.pre_formal_review"></a></span><a class="link" href="acknowledgments.html#boost_optional.acknowledgments.pre_formal_review">Pre-formal
|
||||
review</a>
|
||||
</h4>
|
||||
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
|
||||
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
|
||||
<li class="listitem">
|
||||
Peter Dimov suggested the name 'optional', and was the first to point out
|
||||
the need for aligned storage.
|
||||
</li>
|
||||
Peter Dimov suggested the name 'optional', and was the first to point out
|
||||
the need for aligned storage.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
Douglas Gregor developed 'type_with_alignment', and later Eric Friedman coded
|
||||
'aligned_storage', which are the core of the optional class implementation.
|
||||
</li>
|
||||
Douglas Gregor developed 'type_with_alignment', and later Eric Friedman
|
||||
coded 'aligned_storage', which are the core of the optional class implementation.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
Andrei Alexandrescu and Brian Parker also worked with aligned storage techniques
|
||||
and their work influenced the current implementation.
|
||||
</li>
|
||||
Andrei Alexandrescu and Brian Parker also worked with aligned storage techniques
|
||||
and their work influenced the current implementation.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
Gennadiy Rozental made extensive and important comments which shaped the
|
||||
design.
|
||||
</li>
|
||||
Gennadiy Rozental made extensive and important comments which shaped the
|
||||
design.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
Vesa Karvonen and Douglas Gregor made quite useful comparisons between optional,
|
||||
variant and any; and made other relevant comments.
|
||||
</li>
|
||||
Vesa Karvonen and Douglas Gregor made quite useful comparisons between
|
||||
optional, variant and any; and made other relevant comments.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
Douglas Gregor and Peter Dimov commented on comparisons and evaluation in
|
||||
boolean contexts.
|
||||
</li>
|
||||
Douglas Gregor and Peter Dimov commented on comparisons and evaluation
|
||||
in boolean contexts.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
Eric Friedman helped understand the issues involved with aligned storage,
|
||||
move/copy operations and exception safety.
|
||||
</li>
|
||||
Eric Friedman helped understand the issues involved with aligned storage,
|
||||
move/copy operations and exception safety.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
Many others have participated with useful comments: Aleksey Gurotov, Kevlin
|
||||
Henney, David Abrahams, and others I can't recall.
|
||||
</li>
|
||||
Many others have participated with useful comments: Aleksey Gurotov, Kevlin
|
||||
Henney, David Abrahams, and others I can't recall.
|
||||
</li>
|
||||
</ul></div>
|
||||
<a name="boost_optional.acknowledgments.post_formal_review"></a><h4>
|
||||
<a name="id584068"></a>
|
||||
<a class="link" href="acknowledgments.html#boost_optional.acknowledgments.post_formal_review">Post-formal
|
||||
<h4>
|
||||
<a name="boost_optional.acknowledgments.h1"></a>
|
||||
<span class="phrase"><a name="boost_optional.acknowledgments.post_formal_review"></a></span><a class="link" href="acknowledgments.html#boost_optional.acknowledgments.post_formal_review">Post-formal
|
||||
review</a>
|
||||
</h4>
|
||||
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
|
||||
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
|
||||
<li class="listitem">
|
||||
William Kempf carefully considered the originally proposed interface and
|
||||
suggested the new interface which is currently used. He also started and
|
||||
fueled the discussion about the analogy optional<>/smart pointer and
|
||||
about relational operators.
|
||||
</li>
|
||||
William Kempf carefully considered the originally proposed interface and
|
||||
suggested the new interface which is currently used. He also started and
|
||||
fueled the discussion about the analogy optional<>/smart pointer
|
||||
and about relational operators.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
Peter Dimov, Joel de Guzman, David Abrahams, Tanton Gibbs and Ian Hanson
|
||||
focused on the relational semantics of optional (originally undefined); concluding
|
||||
with the fact that the pointer-like interface doesn't make it a pointer so
|
||||
it shall have deep relational operators.
|
||||
</li>
|
||||
Peter Dimov, Joel de Guzman, David Abrahams, Tanton Gibbs and Ian Hanson
|
||||
focused on the relational semantics of optional (originally undefined);
|
||||
concluding with the fact that the pointer-like interface doesn't make it
|
||||
a pointer so it shall have deep relational operators.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
Augustus Saunders also explored the different relational semantics between
|
||||
optional<> and a pointer and developed the OptionalPointee concept
|
||||
as an aid against potential conflicts on generic code.
|
||||
</li>
|
||||
Augustus Saunders also explored the different relational semantics between
|
||||
optional<> and a pointer and developed the OptionalPointee concept
|
||||
as an aid against potential conflicts on generic code.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
Joel de Guzman noticed that optional<> can be seen as an API on top
|
||||
of variant<T,nil_t>.
|
||||
</li>
|
||||
Joel de Guzman noticed that optional<> can be seen as an API on top
|
||||
of variant<T,nil_t>.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
Dave Gomboc explained the meaning and usage of the Haskell analog to optional<>:
|
||||
the Maybe type constructor (analogy originally pointed out by David Sankel).
|
||||
</li>
|
||||
Dave Gomboc explained the meaning and usage of the Haskell analog to optional<>:
|
||||
the Maybe type constructor (analogy originally pointed out by David Sankel).
|
||||
</li>
|
||||
<li class="listitem">
|
||||
Other comments were posted by Vincent Finn, Anthony Williams, Ed Brey, Rob
|
||||
Stewart, and others.
|
||||
</li>
|
||||
Other comments were posted by Vincent Finn, Anthony Williams, Ed Brey,
|
||||
Rob Stewart, and others.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
Joel de Guzman made the case for the support of references and helped with
|
||||
the proper semantics.
|
||||
</li>
|
||||
Joel de Guzman made the case for the support of references and helped with
|
||||
the proper semantics.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
Mat Marcus shown the virtues of a value-oriented interface, influencing the
|
||||
current design, and contributed the idea of "none".
|
||||
</li>
|
||||
Mat Marcus shown the virtues of a value-oriented interface, influencing
|
||||
the current design, and contributed the idea of "none".
|
||||
</li>
|
||||
</ul></div>
|
||||
</div>
|
||||
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
|
||||
<td align="left"></td>
|
||||
<td align="right"><div class="copyright-footer">Copyright <EFBFBD> 2003 -2007 Fernando Luis Cacciola Carballal<p>
|
||||
<td align="right"><div class="copyright-footer">Copyright © 2003-2007 Fernando Luis Cacciola Carballal<p>
|
||||
Distributed under the Boost Software License, Version 1.0. (See accompanying
|
||||
file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
|
||||
</p>
|
||||
@ -119,7 +119,7 @@
|
||||
</tr></table>
|
||||
<hr>
|
||||
<div class="spirit-nav">
|
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<a accesskey="p" href="dependencies_and_portability.html"><img src="../../../../../doc/html/images/prev.png" alt="Prev"></a><a accesskey="u" href="../index.html"><img src="../../../../../doc/html/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../../../doc/html/images/home.png" alt="Home"></a>
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</html>
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@ -1,11 +1,11 @@
|
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<a name="boost_optional.dependencies_and_portability"></a><a class="link" href="dependencies_and_portability.html" title="Dependencies and Portability">Dependencies
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and Portability</a>
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<td align="right"><div class="copyright-footer">Copyright <EFBFBD> 2003 -2007 Fernando Luis Cacciola Carballal<p>
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<td align="right"><div class="copyright-footer">Copyright © 2003-2007 Fernando Luis Cacciola Carballal<p>
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Distributed under the Boost Software License, Version 1.0. (See accompanying
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file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
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<div class="section" title="Development">
|
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<div class="section boost_optional_development">
|
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<a name="boost_optional.development"></a><a class="link" href="development.html" title="Development">Development</a>
|
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</h2></div></div></div>
|
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@ -31,7 +31,7 @@
|
||||
<dt><span class="section"><a href="development.html#boost_optional.development.the_semantics">The semantics</a></span></dt>
|
||||
<dt><span class="section"><a href="development.html#boost_optional.development.the_interface">The Interface</a></span></dt>
|
||||
</dl></div>
|
||||
<div class="section" title="The models">
|
||||
<div class="section boost_optional_development_the_models">
|
||||
<div class="titlepage"><div><div><h3 class="title">
|
||||
<a name="boost_optional.development.the_models"></a><a class="link" href="development.html#boost_optional.development.the_models" title="The models">The models</a>
|
||||
</h3></div></div></div>
|
||||
@ -96,7 +96,7 @@
|
||||
value of <code class="computeroutput"><span class="identifier">T</span></code> or nothing.
|
||||
</p>
|
||||
<p>
|
||||
As of this writing I don't know of any precedence for a variable-size fixed-capacity
|
||||
As of this writing I don't know of any precedent for a variable-size fixed-capacity
|
||||
(of 1) stack-based container model for optional values, yet I believe this
|
||||
is the consequence of the lack of practical implementations of such a container
|
||||
rather than an inherent shortcoming of the container model.
|
||||
@ -110,65 +110,65 @@
|
||||
<p>
|
||||
Discriminated-union:
|
||||
</p>
|
||||
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
|
||||
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
|
||||
<li class="listitem">
|
||||
<span class="bold"><strong>deep-copy</strong></span> semantics: copies of the variant
|
||||
implies copies of the value.
|
||||
</li>
|
||||
<span class="bold"><strong>deep-copy</strong></span> semantics: copies of the variant
|
||||
implies copies of the value.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
<span class="bold"><strong>deep-relational</strong></span> semantics: comparisons
|
||||
between variants matches both current types and values
|
||||
</li>
|
||||
<span class="bold"><strong>deep-relational</strong></span> semantics: comparisons
|
||||
between variants matches both current types and values
|
||||
</li>
|
||||
<li class="listitem">
|
||||
If the variant's current type is <code class="computeroutput"><span class="identifier">T</span></code>,
|
||||
it is modeling an <span class="emphasis"><em>initialized</em></span> optional.
|
||||
</li>
|
||||
If the variant's current type is <code class="computeroutput"><span class="identifier">T</span></code>,
|
||||
it is modeling an <span class="emphasis"><em>initialized</em></span> optional.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
If the variant's current type is not <code class="computeroutput"><span class="identifier">T</span></code>,
|
||||
it is modeling an <span class="emphasis"><em>uninitialized</em></span> optional.
|
||||
</li>
|
||||
If the variant's current type is not <code class="computeroutput"><span class="identifier">T</span></code>,
|
||||
it is modeling an <span class="emphasis"><em>uninitialized</em></span> optional.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
Testing if the variant's current type is <code class="computeroutput"><span class="identifier">T</span></code>
|
||||
models testing if the optional is initialized
|
||||
</li>
|
||||
Testing if the variant's current type is <code class="computeroutput"><span class="identifier">T</span></code>
|
||||
models testing if the optional is initialized
|
||||
</li>
|
||||
<li class="listitem">
|
||||
Trying to extract a <code class="computeroutput"><span class="identifier">T</span></code> from
|
||||
a variant when its current type is not <code class="computeroutput"><span class="identifier">T</span></code>,
|
||||
models the undefined behavior of trying to access the value of an uninitialized
|
||||
optional
|
||||
</li>
|
||||
Trying to extract a <code class="computeroutput"><span class="identifier">T</span></code>
|
||||
from a variant when its current type is not <code class="computeroutput"><span class="identifier">T</span></code>,
|
||||
models the undefined behavior of trying to access the value of an uninitialized
|
||||
optional
|
||||
</li>
|
||||
</ul></div>
|
||||
<p>
|
||||
Single-element container:
|
||||
</p>
|
||||
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
|
||||
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
|
||||
<li class="listitem">
|
||||
<span class="bold"><strong>deep-copy</strong></span> semantics: copies of the container
|
||||
implies copies of the value.
|
||||
</li>
|
||||
<span class="bold"><strong>deep-copy</strong></span> semantics: copies of the container
|
||||
implies copies of the value.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
<span class="bold"><strong>deep-relational</strong></span> semantics: comparisons
|
||||
between containers compare container size and if match, contained value
|
||||
</li>
|
||||
<span class="bold"><strong>deep-relational</strong></span> semantics: comparisons
|
||||
between containers compare container size and if match, contained value
|
||||
</li>
|
||||
<li class="listitem">
|
||||
If the container is not empty (contains an object of type <code class="computeroutput"><span class="identifier">T</span></code>), it is modeling an <span class="emphasis"><em>initialized</em></span>
|
||||
optional.
|
||||
</li>
|
||||
If the container is not empty (contains an object of type <code class="computeroutput"><span class="identifier">T</span></code>), it is modeling an <span class="emphasis"><em>initialized</em></span>
|
||||
optional.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
If the container is empty, it is modeling an <span class="emphasis"><em>uninitialized</em></span>
|
||||
optional.
|
||||
</li>
|
||||
If the container is empty, it is modeling an <span class="emphasis"><em>uninitialized</em></span>
|
||||
optional.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
Testing if the container is empty models testing if the optional is initialized
|
||||
</li>
|
||||
Testing if the container is empty models testing if the optional is initialized
|
||||
</li>
|
||||
<li class="listitem">
|
||||
Trying to extract a <code class="computeroutput"><span class="identifier">T</span></code> from
|
||||
an empty container models the undefined behavior of trying to access the
|
||||
value of an uninitialized optional
|
||||
</li>
|
||||
Trying to extract a <code class="computeroutput"><span class="identifier">T</span></code>
|
||||
from an empty container models the undefined behavior of trying to access
|
||||
the value of an uninitialized optional
|
||||
</li>
|
||||
</ul></div>
|
||||
</div>
|
||||
<div class="section" title="The semantics">
|
||||
<div class="section boost_optional_development_the_semantics">
|
||||
<div class="titlepage"><div><div><h3 class="title">
|
||||
<a name="boost_optional.development.the_semantics"></a><a class="link" href="development.html#boost_optional.development.the_semantics" title="The semantics">The semantics</a>
|
||||
</h3></div></div></div>
|
||||
@ -193,58 +193,59 @@
|
||||
We can draw from the purpose of <code class="computeroutput"><span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">></span></code>
|
||||
the required basic semantics:
|
||||
</p>
|
||||
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
|
||||
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
|
||||
<li class="listitem">
|
||||
<span class="bold"><strong>Default Construction:</strong></span> To introduce a formally
|
||||
uninitialized wrapped object.
|
||||
</li>
|
||||
<span class="bold"><strong>Default Construction:</strong></span> To introduce a
|
||||
formally uninitialized wrapped object.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
<span class="bold"><strong>Direct Value Construction via copy:</strong></span> To
|
||||
introduce a formally initialized wrapped object whose value is obtained
|
||||
as a copy of some object.
|
||||
</li>
|
||||
<span class="bold"><strong>Direct Value Construction via copy:</strong></span>
|
||||
To introduce a formally initialized wrapped object whose value is obtained
|
||||
as a copy of some object.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
<span class="bold"><strong>Deep Copy Construction:</strong></span> To obtain a new
|
||||
yet equivalent wrapped object.
|
||||
</li>
|
||||
<span class="bold"><strong>Deep Copy Construction:</strong></span> To obtain a
|
||||
new yet equivalent wrapped object.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
<span class="bold"><strong>Direct Value Assignment (upon initialized):</strong></span>
|
||||
To assign a value to the wrapped object.
|
||||
</li>
|
||||
<span class="bold"><strong>Direct Value Assignment (upon initialized):</strong></span>
|
||||
To assign a value to the wrapped object.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
<span class="bold"><strong>Direct Value Assignment (upon uninitialized):</strong></span>
|
||||
To initialize the wrapped object with a value obtained as a copy of some
|
||||
object.
|
||||
</li>
|
||||
<span class="bold"><strong>Direct Value Assignment (upon uninitialized):</strong></span>
|
||||
To initialize the wrapped object with a value obtained as a copy of some
|
||||
object.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
<span class="bold"><strong>Assignment (upon initialized):</strong></span> To assign
|
||||
to the wrapped object the value of another wrapped object.
|
||||
</li>
|
||||
<span class="bold"><strong>Assignment (upon initialized):</strong></span> To assign
|
||||
to the wrapped object the value of another wrapped object.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
<span class="bold"><strong>Assignment (upon uninitialized):</strong></span> To initialize
|
||||
the wrapped object with value of another wrapped object.
|
||||
</li>
|
||||
<span class="bold"><strong>Assignment (upon uninitialized):</strong></span> To
|
||||
initialize the wrapped object with value of another wrapped object.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
<span class="bold"><strong>Deep Relational Operations (when supported by the
|
||||
type T):</strong></span> To compare wrapped object values taking into account
|
||||
the presence of uninitialized states.
|
||||
</li>
|
||||
<span class="bold"><strong>Deep Relational Operations (when supported by the
|
||||
type T):</strong></span> To compare wrapped object values taking into account
|
||||
the presence of uninitialized states.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
<span class="bold"><strong>Value access:</strong></span> To unwrap the wrapped object.
|
||||
</li>
|
||||
<span class="bold"><strong>Value access:</strong></span> To unwrap the wrapped
|
||||
object.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
<span class="bold"><strong>Initialization state query:</strong></span> To determine
|
||||
if the object is formally initialized or not.
|
||||
</li>
|
||||
<span class="bold"><strong>Initialization state query:</strong></span> To determine
|
||||
if the object is formally initialized or not.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
<span class="bold"><strong>Swap:</strong></span> To exchange wrapped objects. (with
|
||||
whatever exception safety guarantees are provided by <code class="computeroutput"><span class="identifier">T</span></code>'s
|
||||
swap).
|
||||
</li>
|
||||
<span class="bold"><strong>Swap:</strong></span> To exchange wrapped objects. (with
|
||||
whatever exception safety guarantees are provided by <code class="computeroutput"><span class="identifier">T</span></code>'s
|
||||
swap).
|
||||
</li>
|
||||
<li class="listitem">
|
||||
<span class="bold"><strong>De-initialization:</strong></span> To release the wrapped
|
||||
object (if any) and leave the wrapper in the uninitialized state.
|
||||
</li>
|
||||
<span class="bold"><strong>De-initialization:</strong></span> To release the wrapped
|
||||
object (if any) and leave the wrapper in the uninitialized state.
|
||||
</li>
|
||||
</ul></div>
|
||||
<p>
|
||||
Additional operations are useful, such as converting constructors and converting
|
||||
@ -252,7 +253,7 @@
|
||||
via a pointer to the wrapped object or null.
|
||||
</p>
|
||||
</div>
|
||||
<div class="section" title="The Interface">
|
||||
<div class="section boost_optional_development_the_interface">
|
||||
<div class="titlepage"><div><div><h3 class="title">
|
||||
<a name="boost_optional.development.the_interface"></a><a class="link" href="development.html#boost_optional.development.the_interface" title="The Interface">The Interface</a>
|
||||
</h3></div></div></div>
|
||||
@ -291,9 +292,9 @@
|
||||
operations not provided by <code class="computeroutput"><span class="identifier">T</span></code>
|
||||
itself which are supported by a special interface.
|
||||
</p>
|
||||
<a name="boost_optional.development.the_interface.lexically_hinted_value_access_in_the_presence_of_possibly_untitialized_optional_objects__the_operators___and___gt_"></a><h5>
|
||||
<a name="id555569"></a>
|
||||
<a class="link" href="development.html#boost_optional.development.the_interface.lexically_hinted_value_access_in_the_presence_of_possibly_untitialized_optional_objects__the_operators___and___gt_">Lexically-hinted
|
||||
<h5>
|
||||
<a name="boost_optional.development.the_interface.h0"></a>
|
||||
<span class="phrase"><a name="boost_optional.development.the_interface.lexically_hinted_value_access_in_the_presence_of_possibly_untitialized_optional_objects__the_operators___and___gt_"></a></span><a class="link" href="development.html#boost_optional.development.the_interface.lexically_hinted_value_access_in_the_presence_of_possibly_untitialized_optional_objects__the_operators___and___gt_">Lexically-hinted
|
||||
Value Access in the presence of possibly untitialized optional objects: The
|
||||
operators * and -></a>
|
||||
</h5>
|
||||
@ -301,7 +302,7 @@
|
||||
A relevant feature of a pointer is that it can have a <span class="bold"><strong>null
|
||||
pointer value</strong></span>. This is a <span class="emphasis"><em>special</em></span> value which
|
||||
is used to indicate that the pointer is not referring to any object at all.
|
||||
In other words, null pointer values convey the notion of inexistent objects.
|
||||
In other words, null pointer values convey the notion of nonexistent objects.
|
||||
</p>
|
||||
<p>
|
||||
This meaning of the null pointer value allowed pointers to became a <span class="emphasis"><em>de
|
||||
@ -309,7 +310,7 @@
|
||||
to do to refer to a value which you don't really have is to use a null pointer
|
||||
value of the appropriate type. Pointers have been used for decades—from
|
||||
the days of C APIs to modern C++ libraries—to <span class="emphasis"><em>refer</em></span>
|
||||
to optional (that is, possibly inexistent) objects; particularly as optional
|
||||
to optional (that is, possibly nonexistent) objects; particularly as optional
|
||||
arguments to a function, but also quite often as optional data members.
|
||||
</p>
|
||||
<p>
|
||||
@ -356,9 +357,9 @@
|
||||
possible undefined value because of the idiomatic aid present in the <a href="../../../../utility/OptionalPointee.html" target="_top">OptionalPointee</a> concept
|
||||
incarnated by pointers.
|
||||
</p>
|
||||
<a name="boost_optional.development.the_interface.optional_lt_t_gt__as_a_model_of_optionalpointee"></a><h5>
|
||||
<a name="id555831"></a>
|
||||
<a class="link" href="development.html#boost_optional.development.the_interface.optional_lt_t_gt__as_a_model_of_optionalpointee">Optional<T>
|
||||
<h5>
|
||||
<a name="boost_optional.development.the_interface.h1"></a>
|
||||
<span class="phrase"><a name="boost_optional.development.the_interface.optional_lt_t_gt__as_a_model_of_optionalpointee"></a></span><a class="link" href="development.html#boost_optional.development.the_interface.optional_lt_t_gt__as_a_model_of_optionalpointee">Optional<T>
|
||||
as a model of OptionalPointee</a>
|
||||
</h5>
|
||||
<p>
|
||||
@ -367,9 +368,9 @@
|
||||
about the possibly uninitialized state appealing to the familiar pointer
|
||||
semantics w.r.t. to null pointers.
|
||||
</p>
|
||||
<div class="warning" title="Warning"><table border="0" summary="Warning">
|
||||
<div class="warning"><table border="0" summary="Warning">
|
||||
<tr>
|
||||
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Warning]" src="../../../../../doc/html/images/warning.png"></td>
|
||||
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Warning]" src="../../../../../doc/src/images/warning.png"></td>
|
||||
<th align="left">Warning</th>
|
||||
</tr>
|
||||
<tr><td align="left" valign="top"><p>
|
||||
@ -398,7 +399,7 @@
|
||||
</div>
|
||||
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
|
||||
<td align="left"></td>
|
||||
<td align="right"><div class="copyright-footer">Copyright <EFBFBD> 2003 -2007 Fernando Luis Cacciola Carballal<p>
|
||||
<td align="right"><div class="copyright-footer">Copyright © 2003-2007 Fernando Luis Cacciola Carballal<p>
|
||||
Distributed under the Boost Software License, Version 1.0. (See accompanying
|
||||
file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
|
||||
</p>
|
||||
@ -406,7 +407,7 @@
|
||||
</tr></table>
|
||||
<hr>
|
||||
<div class="spirit-nav">
|
||||
<a accesskey="p" href="../index.html"><img src="../../../../../doc/html/images/prev.png" alt="Prev"></a><a accesskey="u" href="../index.html"><img src="../../../../../doc/html/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../../../doc/html/images/home.png" alt="Home"></a><a accesskey="n" href="synopsis.html"><img src="../../../../../doc/html/images/next.png" alt="Next"></a>
|
||||
<a accesskey="p" href="../index.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../index.html"><img src="../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="synopsis.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a>
|
||||
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|
||||
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|
||||
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|
||||
|
||||
@ -1,11 +1,11 @@
|
||||
<html>
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=US-ASCII">
|
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<title>Examples</title>
|
||||
<link rel="stylesheet" href="../boostbook.css" type="text/css">
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<meta name="generator" content="DocBook XSL Stylesheets V1.75.2">
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<link rel="home" href="../index.html" title="Chapter<EFBFBD>1.<2E>Boost.Optional">
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<meta name="generator" content="DocBook XSL Stylesheets V1.77.1">
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<link rel="home" href="../index.html" title="Chapter 1. Boost.Optional">
|
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|
||||
<link rel="prev" href="detailed_semantics.html" title="Detailed Semantics">
|
||||
<link rel="next" href="optional_references.html" title="Optional references">
|
||||
</head>
|
||||
@ -13,16 +13,16 @@
|
||||
<table cellpadding="2" width="100%"><tr>
|
||||
<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../boost.png"></td>
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||||
<td align="center"><a href="../../../../../index.html">Home</a></td>
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||||
<td align="center"><a href="../../../../libraries.htm">Libraries</a></td>
|
||||
<td align="center"><a href="../../../../../libs/libraries.htm">Libraries</a></td>
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<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td>
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||||
<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td>
|
||||
<td align="center"><a href="../../../../../more/index.htm">More</a></td>
|
||||
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|
||||
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|
||||
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<a accesskey="p" href="detailed_semantics.html"><img src="../../../../../doc/html/images/prev.png" alt="Prev"></a><a accesskey="u" href="../index.html"><img src="../../../../../doc/html/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../../../doc/html/images/home.png" alt="Home"></a><a accesskey="n" href="optional_references.html"><img src="../../../../../doc/html/images/next.png" alt="Next"></a>
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||||
<a accesskey="p" href="detailed_semantics.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../index.html"><img src="../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="optional_references.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a>
|
||||
</div>
|
||||
<div class="section" title="Examples">
|
||||
<div class="section boost_optional_examples">
|
||||
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
|
||||
<a name="boost_optional.examples"></a><a class="link" href="examples.html" title="Examples">Examples</a>
|
||||
</h2></div></div></div>
|
||||
@ -36,7 +36,7 @@
|
||||
<dt><span class="section"><a href="examples.html#boost_optional.examples.bypassing_expensive_unnecessary_default_construction">Bypassing
|
||||
expensive unnecessary default construction</a></span></dt>
|
||||
</dl></div>
|
||||
<div class="section" title="Optional return values">
|
||||
<div class="section boost_optional_examples_optional_return_values">
|
||||
<div class="titlepage"><div><div><h3 class="title">
|
||||
<a name="boost_optional.examples.optional_return_values"></a><a class="link" href="examples.html#boost_optional.examples.optional_return_values" title="Optional return values">Optional
|
||||
return values</a>
|
||||
@ -45,19 +45,19 @@
|
||||
<span class="special">{</span>
|
||||
<span class="keyword">if</span> <span class="special">(</span> <span class="special">!</span><span class="identifier">queue</span><span class="special">.</span><span class="identifier">empty</span><span class="special">()</span> <span class="special">)</span>
|
||||
<span class="keyword">return</span> <span class="identifier">optional</span><span class="special"><</span><span class="keyword">char</span><span class="special">>(</span><span class="identifier">queue</span><span class="special">.</span><span class="identifier">top</span><span class="special">());</span>
|
||||
<span class="keyword">else</span> <span class="keyword">return</span> <span class="identifier">optional</span><span class="special"><</span><span class="keyword">char</span><span class="special">>();</span> <span class="comment">// uninitialized
|
||||
</span><span class="special">}</span>
|
||||
<span class="keyword">else</span> <span class="keyword">return</span> <span class="identifier">optional</span><span class="special"><</span><span class="keyword">char</span><span class="special">>();</span> <span class="comment">// uninitialized</span>
|
||||
<span class="special">}</span>
|
||||
|
||||
<span class="keyword">void</span> <span class="identifier">receive_async_message</span><span class="special">()</span>
|
||||
<span class="special">{</span>
|
||||
<span class="identifier">optional</span><span class="special"><</span><span class="keyword">char</span><span class="special">></span> <span class="identifier">rcv</span> <span class="special">;</span>
|
||||
<span class="comment">// The safe boolean conversion from 'rcv' is used here.
|
||||
</span> <span class="keyword">while</span> <span class="special">(</span> <span class="special">(</span><span class="identifier">rcv</span> <span class="special">=</span> <span class="identifier">get_async_input</span><span class="special">())</span> <span class="special">&&</span> <span class="special">!</span><span class="identifier">timeout</span><span class="special">()</span> <span class="special">)</span>
|
||||
<span class="comment">// The safe boolean conversion from 'rcv' is used here.</span>
|
||||
<span class="keyword">while</span> <span class="special">(</span> <span class="special">(</span><span class="identifier">rcv</span> <span class="special">=</span> <span class="identifier">get_async_input</span><span class="special">())</span> <span class="special">&&</span> <span class="special">!</span><span class="identifier">timeout</span><span class="special">()</span> <span class="special">)</span>
|
||||
<span class="identifier">output</span><span class="special">(*</span><span class="identifier">rcv</span><span class="special">);</span>
|
||||
<span class="special">}</span>
|
||||
</pre>
|
||||
</div>
|
||||
<div class="section" title="Optional local variables">
|
||||
<div class="section boost_optional_examples_optional_local_variables">
|
||||
<div class="titlepage"><div><div><h3 class="title">
|
||||
<a name="boost_optional.examples.optional_local_variables"></a><a class="link" href="examples.html#boost_optional.examples.optional_local_variables" title="Optional local variables">Optional
|
||||
local variables</a>
|
||||
@ -65,12 +65,12 @@
|
||||
<pre class="programlisting"><span class="identifier">optional</span><span class="special"><</span><span class="identifier">string</span><span class="special">></span> <span class="identifier">name</span> <span class="special">;</span>
|
||||
<span class="keyword">if</span> <span class="special">(</span> <span class="identifier">database</span><span class="special">.</span><span class="identifier">open</span><span class="special">()</span> <span class="special">)</span>
|
||||
<span class="special">{</span>
|
||||
<span class="identifier">name</span><span class="special">.</span><span class="identifier">reset</span> <span class="special">(</span> <span class="identifier">database</span><span class="special">.</span><span class="identifier">lookup</span><span class="special">(</span><span class="identifier">employer_name</span><span class="special">)</span> <span class="special">)</span> <span class="special">;</span>
|
||||
<span class="identifier">name</span> <span class="special">=</span> <span class="identifier">database</span><span class="special">.</span><span class="identifier">lookup</span><span class="special">(</span><span class="identifier">employer_name</span><span class="special">)</span> <span class="special">;</span>
|
||||
<span class="special">}</span>
|
||||
<span class="keyword">else</span>
|
||||
<span class="special">{</span>
|
||||
<span class="keyword">if</span> <span class="special">(</span> <span class="identifier">can_ask_user</span> <span class="special">)</span>
|
||||
<span class="identifier">name</span><span class="special">.</span><span class="identifier">reset</span> <span class="special">(</span> <span class="identifier">user</span><span class="special">.</span><span class="identifier">ask</span><span class="special">(</span><span class="identifier">employer_name</span><span class="special">)</span> <span class="special">)</span> <span class="special">;</span>
|
||||
<span class="identifier">name</span> <span class="special">=</span> <span class="identifier">user</span><span class="special">.</span><span class="identifier">ask</span><span class="special">(</span><span class="identifier">employer_name</span><span class="special">)</span> <span class="special">;</span>
|
||||
<span class="special">}</span>
|
||||
|
||||
<span class="keyword">if</span> <span class="special">(</span> <span class="identifier">name</span> <span class="special">)</span>
|
||||
@ -78,7 +78,7 @@
|
||||
<span class="keyword">else</span> <span class="identifier">print</span><span class="special">(</span><span class="string">"employer's name not found!"</span><span class="special">);</span>
|
||||
</pre>
|
||||
</div>
|
||||
<div class="section" title="Optional data members">
|
||||
<div class="section boost_optional_examples_optional_data_members">
|
||||
<div class="titlepage"><div><div><h3 class="title">
|
||||
<a name="boost_optional.examples.optional_data_members"></a><a class="link" href="examples.html#boost_optional.examples.optional_data_members" title="Optional data members">Optional
|
||||
data members</a>
|
||||
@ -89,14 +89,14 @@
|
||||
|
||||
<span class="identifier">figure</span><span class="special">()</span>
|
||||
<span class="special">{</span>
|
||||
<span class="comment">// data member 'm_clipping_rect' is uninitialized at this point.
|
||||
</span> <span class="special">}</span>
|
||||
<span class="comment">// data member 'm_clipping_rect' is uninitialized at this point.</span>
|
||||
<span class="special">}</span>
|
||||
|
||||
<span class="keyword">void</span> <span class="identifier">clip_in_rect</span> <span class="special">(</span> <span class="identifier">rect</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">rect</span> <span class="special">)</span>
|
||||
<span class="special">{</span>
|
||||
<span class="special">....</span>
|
||||
<span class="identifier">m_clipping_rect</span><span class="special">.</span><span class="identifier">reset</span> <span class="special">(</span> <span class="identifier">rect</span> <span class="special">)</span> <span class="special">;</span> <span class="comment">// initialized here.
|
||||
</span> <span class="special">}</span>
|
||||
<span class="identifier">m_clipping_rect</span> <span class="special">=</span> <span class="identifier">rect</span> <span class="special">;</span> <span class="comment">// initialized here.</span>
|
||||
<span class="special">}</span>
|
||||
|
||||
<span class="keyword">void</span> <span class="identifier">draw</span> <span class="special">(</span> <span class="identifier">canvas</span><span class="special">&</span> <span class="identifier">cvs</span> <span class="special">)</span>
|
||||
<span class="special">{</span>
|
||||
@ -106,8 +106,8 @@
|
||||
<span class="identifier">cvs</span><span class="special">.</span><span class="identifier">drawXXX</span><span class="special">(..);</span>
|
||||
<span class="special">}</span>
|
||||
|
||||
<span class="comment">// this can return NULL.
|
||||
</span> <span class="identifier">rect</span> <span class="keyword">const</span><span class="special">*</span> <span class="identifier">get_clipping_rect</span><span class="special">()</span> <span class="special">{</span> <span class="keyword">return</span> <span class="identifier">get_pointer</span><span class="special">(</span><span class="identifier">m_clipping_rect</span><span class="special">);</span> <span class="special">}</span>
|
||||
<span class="comment">// this can return NULL.</span>
|
||||
<span class="identifier">rect</span> <span class="keyword">const</span><span class="special">*</span> <span class="identifier">get_clipping_rect</span><span class="special">()</span> <span class="special">{</span> <span class="keyword">return</span> <span class="identifier">get_pointer</span><span class="special">(</span><span class="identifier">m_clipping_rect</span><span class="special">);</span> <span class="special">}</span>
|
||||
|
||||
<span class="keyword">private</span> <span class="special">:</span>
|
||||
|
||||
@ -116,7 +116,7 @@
|
||||
<span class="special">};</span>
|
||||
</pre>
|
||||
</div>
|
||||
<div class="section" title="Bypassing expensive unnecessary default construction">
|
||||
<div class="section boost_optional_examples_bypassing_expensive_unnecessary_default_construction">
|
||||
<div class="titlepage"><div><div><h3 class="title">
|
||||
<a name="boost_optional.examples.bypassing_expensive_unnecessary_default_construction"></a><a class="link" href="examples.html#boost_optional.examples.bypassing_expensive_unnecessary_default_construction" title="Bypassing expensive unnecessary default construction">Bypassing
|
||||
expensive unnecessary default construction</a>
|
||||
@ -133,7 +133,7 @@
|
||||
</div>
|
||||
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
|
||||
<td align="left"></td>
|
||||
<td align="right"><div class="copyright-footer">Copyright <EFBFBD> 2003 -2007 Fernando Luis Cacciola Carballal<p>
|
||||
<td align="right"><div class="copyright-footer">Copyright © 2003-2007 Fernando Luis Cacciola Carballal<p>
|
||||
Distributed under the Boost Software License, Version 1.0. (See accompanying
|
||||
file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
|
||||
</p>
|
||||
@ -141,7 +141,7 @@
|
||||
</tr></table>
|
||||
<hr>
|
||||
<div class="spirit-nav">
|
||||
<a accesskey="p" href="detailed_semantics.html"><img src="../../../../../doc/html/images/prev.png" alt="Prev"></a><a accesskey="u" href="../index.html"><img src="../../../../../doc/html/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../../../doc/html/images/home.png" alt="Home"></a><a accesskey="n" href="optional_references.html"><img src="../../../../../doc/html/images/next.png" alt="Next"></a>
|
||||
<a accesskey="p" href="detailed_semantics.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../index.html"><img src="../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="optional_references.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a>
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|
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@ -1,11 +1,11 @@
|
||||
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<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td>
|
||||
<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td>
|
||||
<td align="center"><a href="../../../../../more/index.htm">More</a></td>
|
||||
</tr></table>
|
||||
<hr>
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||||
<div class="spirit-nav">
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<a accesskey="p" href="a_note_about_optional_bool_.html"><img src="../../../../../doc/html/images/prev.png" alt="Prev"></a><a accesskey="u" href="../index.html"><img src="../../../../../doc/html/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../../../doc/html/images/home.png" alt="Home"></a><a accesskey="n" href="type_requirements.html"><img src="../../../../../doc/html/images/next.png" alt="Next"></a>
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<a accesskey="p" href="a_note_about_optional_bool_.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../index.html"><img src="../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="type_requirements.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a>
|
||||
</div>
|
||||
<div class="section" title="Exception Safety Guarantees">
|
||||
<div class="section boost_optional_exception_safety_guarantees">
|
||||
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
|
||||
<a name="boost_optional.exception_safety_guarantees"></a><a class="link" href="exception_safety_guarantees.html" title="Exception Safety Guarantees">Exception Safety
|
||||
Guarantees</a>
|
||||
@ -31,21 +31,29 @@
|
||||
Because of the current implementation (see <a class="link" href="implementation_notes.html" title="Implementation Notes">Implementation
|
||||
Notes</a>), all of the assignment methods:
|
||||
</p>
|
||||
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
|
||||
<li class="listitem"><code class="computeroutput"><span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">>::</span><span class="keyword">operator</span><span class="special">=</span> <span class="special">(</span> <span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">></span>
|
||||
<span class="keyword">const</span><span class="special">&</span>
|
||||
<span class="special">)</span></code></li>
|
||||
<li class="listitem"><code class="computeroutput"><span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">>::</span><span class="keyword">operator</span><span class="special">=</span> <span class="special">(</span> <span class="identifier">T</span> <span class="keyword">const</span><span class="special">&</span> <span class="special">)</span></code></li>
|
||||
<li class="listitem"><code class="computeroutput"><span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">U</span><span class="special">></span> <span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">>::</span><span class="keyword">operator</span><span class="special">=</span> <span class="special">(</span> <span class="identifier">optional</span><span class="special"><</span><span class="identifier">U</span><span class="special">></span>
|
||||
<span class="keyword">const</span><span class="special">&</span>
|
||||
<span class="special">)</span></code></li>
|
||||
<li class="listitem"><code class="computeroutput"><span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">InPlaceFactory</span><span class="special">></span> <span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">>::</span><span class="keyword">operator</span><span class="special">=</span> <span class="special">(</span> <span class="identifier">InPlaceFactory</span>
|
||||
<span class="keyword">const</span><span class="special">&</span>
|
||||
<span class="special">)</span></code></li>
|
||||
<li class="listitem"><code class="computeroutput"><span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">TypedInPlaceFactory</span><span class="special">></span> <span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">>::</span><span class="keyword">operator</span><span class="special">=</span> <span class="special">(</span> <span class="identifier">TypedInPlaceFactory</span>
|
||||
<span class="keyword">const</span><span class="special">&</span>
|
||||
<span class="special">)</span> </code></li>
|
||||
<li class="listitem"><code class="computeroutput"><span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">>:::</span><span class="identifier">reset</span> <span class="special">(</span> <span class="identifier">T</span> <span class="keyword">const</span><span class="special">&)</span></code></li>
|
||||
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
|
||||
<li class="listitem">
|
||||
<code class="computeroutput"><span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">>::</span><span class="keyword">operator</span><span class="special">=</span> <span class="special">(</span> <span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">></span> <span class="keyword">const</span><span class="special">&</span> <span class="special">)</span></code>
|
||||
</li>
|
||||
<li class="listitem">
|
||||
<code class="computeroutput"><span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">>::</span><span class="keyword">operator</span><span class="special">=</span> <span class="special">(</span> <span class="identifier">T</span> <span class="keyword">const</span><span class="special">&</span> <span class="special">)</span></code>
|
||||
</li>
|
||||
<li class="listitem">
|
||||
<code class="computeroutput"><span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">U</span><span class="special">></span> <span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">>::</span><span class="keyword">operator</span><span class="special">=</span> <span class="special">(</span> <span class="identifier">optional</span><span class="special"><</span><span class="identifier">U</span><span class="special">></span> <span class="keyword">const</span><span class="special">&</span> <span class="special">)</span></code>
|
||||
</li>
|
||||
<li class="listitem">
|
||||
<code class="computeroutput"><span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">InPlaceFactory</span><span class="special">></span> <span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">>::</span><span class="keyword">operator</span><span class="special">=</span> <span class="special">(</span> <span class="identifier">InPlaceFactory</span>
|
||||
<span class="keyword">const</span><span class="special">&</span>
|
||||
<span class="special">)</span></code>
|
||||
</li>
|
||||
<li class="listitem">
|
||||
<code class="computeroutput"><span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">TypedInPlaceFactory</span><span class="special">></span> <span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">>::</span><span class="keyword">operator</span><span class="special">=</span> <span class="special">(</span> <span class="identifier">TypedInPlaceFactory</span>
|
||||
<span class="keyword">const</span><span class="special">&</span>
|
||||
<span class="special">)</span> </code>
|
||||
</li>
|
||||
<li class="listitem">
|
||||
<code class="computeroutput"><span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">>::</span><span class="identifier">reset</span> <span class="special">(</span> <span class="identifier">T</span> <span class="keyword">const</span><span class="special">&)</span></code>
|
||||
</li>
|
||||
</ul></div>
|
||||
<p>
|
||||
Can only <span class="emphasis"><em>guarantee</em></span> the <span class="underline">basic
|
||||
@ -56,9 +64,13 @@
|
||||
<p>
|
||||
On the other hand, the <span class="emphasis"><em>uninitializing</em></span> methods:
|
||||
</p>
|
||||
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
|
||||
<li class="listitem"><code class="computeroutput"><span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">>::</span><span class="keyword">operator</span><span class="special">=</span> <span class="special">(</span> <span class="identifier">detail</span><span class="special">::</span><span class="identifier">none_t</span> <span class="special">)</span></code></li>
|
||||
<li class="listitem"><code class="computeroutput"><span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">>::</span><span class="identifier">reset</span><span class="special">()</span></code></li>
|
||||
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
|
||||
<li class="listitem">
|
||||
<code class="computeroutput"><span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">>::</span><span class="keyword">operator</span><span class="special">=</span> <span class="special">(</span> <span class="identifier">detail</span><span class="special">::</span><span class="identifier">none_t</span> <span class="special">)</span></code>
|
||||
</li>
|
||||
<li class="listitem">
|
||||
<code class="computeroutput"><span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">>::</span><span class="identifier">reset</span><span class="special">()</span></code>
|
||||
</li>
|
||||
</ul></div>
|
||||
<p>
|
||||
Provide the no-throw guarantee (assuming a no-throw <code class="computeroutput"><span class="identifier">T</span><span class="special">::~</span><span class="identifier">T</span><span class="special">()</span></code>)
|
||||
@ -72,10 +84,10 @@
|
||||
know that <code class="computeroutput"><span class="identifier">optional</span></code>'s assignment
|
||||
and reset has the same guarantees.
|
||||
</p>
|
||||
<pre class="programlisting"><span class="comment">//
|
||||
</span><span class="comment">// Case 1: Exception thrown during assignment.
|
||||
</span><span class="comment">//
|
||||
</span><span class="identifier">T</span> <span class="identifier">v0</span><span class="special">(</span><span class="number">123</span><span class="special">);</span>
|
||||
<pre class="programlisting"><span class="comment">//</span>
|
||||
<span class="comment">// Case 1: Exception thrown during assignment.</span>
|
||||
<span class="comment">//</span>
|
||||
<span class="identifier">T</span> <span class="identifier">v0</span><span class="special">(</span><span class="number">123</span><span class="special">);</span>
|
||||
<span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">></span> <span class="identifier">opt0</span><span class="special">(</span><span class="identifier">v0</span><span class="special">);</span>
|
||||
<span class="keyword">try</span>
|
||||
<span class="special">{</span>
|
||||
@ -83,37 +95,37 @@
|
||||
<span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">></span> <span class="identifier">opt1</span><span class="special">(</span><span class="identifier">v1</span><span class="special">);</span>
|
||||
<span class="identifier">opt0</span> <span class="special">=</span> <span class="identifier">opt1</span> <span class="special">;</span>
|
||||
|
||||
<span class="comment">// If no exception was thrown, assignment succeeded.
|
||||
</span> <span class="identifier">assert</span><span class="special">(</span> <span class="special">*</span><span class="identifier">opt0</span> <span class="special">==</span> <span class="identifier">v1</span> <span class="special">)</span> <span class="special">;</span>
|
||||
<span class="comment">// If no exception was thrown, assignment succeeded.</span>
|
||||
<span class="identifier">assert</span><span class="special">(</span> <span class="special">*</span><span class="identifier">opt0</span> <span class="special">==</span> <span class="identifier">v1</span> <span class="special">)</span> <span class="special">;</span>
|
||||
<span class="special">}</span>
|
||||
<span class="keyword">catch</span><span class="special">(...)</span>
|
||||
<span class="special">{</span>
|
||||
<span class="comment">// If any exception was thrown, 'opt0' is reset to uninitialized.
|
||||
</span> <span class="identifier">assert</span><span class="special">(</span> <span class="special">!</span><span class="identifier">opt0</span> <span class="special">)</span> <span class="special">;</span>
|
||||
<span class="comment">// If any exception was thrown, 'opt0' is reset to uninitialized.</span>
|
||||
<span class="identifier">assert</span><span class="special">(</span> <span class="special">!</span><span class="identifier">opt0</span> <span class="special">)</span> <span class="special">;</span>
|
||||
<span class="special">}</span>
|
||||
|
||||
<span class="comment">//
|
||||
</span><span class="comment">// Case 2: Exception thrown during reset(v)
|
||||
</span><span class="comment">//
|
||||
</span><span class="identifier">T</span> <span class="identifier">v0</span><span class="special">(</span><span class="number">123</span><span class="special">);</span>
|
||||
<span class="comment">//</span>
|
||||
<span class="comment">// Case 2: Exception thrown during reset(v)</span>
|
||||
<span class="comment">//</span>
|
||||
<span class="identifier">T</span> <span class="identifier">v0</span><span class="special">(</span><span class="number">123</span><span class="special">);</span>
|
||||
<span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">></span> <span class="identifier">opt</span><span class="special">(</span><span class="identifier">v0</span><span class="special">);</span>
|
||||
<span class="keyword">try</span>
|
||||
<span class="special">{</span>
|
||||
<span class="identifier">T</span> <span class="identifier">v1</span><span class="special">(</span><span class="number">456</span><span class="special">);</span>
|
||||
<span class="identifier">opt</span><span class="special">.</span><span class="identifier">reset</span> <span class="special">(</span> <span class="identifier">v1</span> <span class="special">)</span> <span class="special">;</span>
|
||||
|
||||
<span class="comment">// If no exception was thrown, reset succeeded.
|
||||
</span> <span class="identifier">assert</span><span class="special">(</span> <span class="special">*</span><span class="identifier">opt</span> <span class="special">==</span> <span class="identifier">v1</span> <span class="special">)</span> <span class="special">;</span>
|
||||
<span class="comment">// If no exception was thrown, reset succeeded.</span>
|
||||
<span class="identifier">assert</span><span class="special">(</span> <span class="special">*</span><span class="identifier">opt</span> <span class="special">==</span> <span class="identifier">v1</span> <span class="special">)</span> <span class="special">;</span>
|
||||
<span class="special">}</span>
|
||||
<span class="keyword">catch</span><span class="special">(...)</span>
|
||||
<span class="special">{</span>
|
||||
<span class="comment">// If any exception was thrown, 'opt' is reset to uninitialized.
|
||||
</span> <span class="identifier">assert</span><span class="special">(</span> <span class="special">!</span><span class="identifier">opt</span> <span class="special">)</span> <span class="special">;</span>
|
||||
<span class="comment">// If any exception was thrown, 'opt' is reset to uninitialized.</span>
|
||||
<span class="identifier">assert</span><span class="special">(</span> <span class="special">!</span><span class="identifier">opt</span> <span class="special">)</span> <span class="special">;</span>
|
||||
<span class="special">}</span>
|
||||
</pre>
|
||||
<a name="boost_optional.exception_safety_guarantees.swap"></a><h4>
|
||||
<a name="id583497"></a>
|
||||
<a class="link" href="exception_safety_guarantees.html#boost_optional.exception_safety_guarantees.swap">Swap</a>
|
||||
<h4>
|
||||
<a name="boost_optional.exception_safety_guarantees.h0"></a>
|
||||
<span class="phrase"><a name="boost_optional.exception_safety_guarantees.swap"></a></span><a class="link" href="exception_safety_guarantees.html#boost_optional.exception_safety_guarantees.swap">Swap</a>
|
||||
</h4>
|
||||
<p>
|
||||
<code class="computeroutput"><span class="keyword">void</span> <span class="identifier">swap</span><span class="special">(</span> <span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">>&,</span>
|
||||
@ -126,7 +138,7 @@
|
||||
</div>
|
||||
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
|
||||
<td align="left"></td>
|
||||
<td align="right"><div class="copyright-footer">Copyright <EFBFBD> 2003 -2007 Fernando Luis Cacciola Carballal<p>
|
||||
<td align="right"><div class="copyright-footer">Copyright © 2003-2007 Fernando Luis Cacciola Carballal<p>
|
||||
Distributed under the Boost Software License, Version 1.0. (See accompanying
|
||||
file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
|
||||
</p>
|
||||
@ -134,7 +146,7 @@
|
||||
</tr></table>
|
||||
<hr>
|
||||
<div class="spirit-nav">
|
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<a accesskey="p" href="a_note_about_optional_bool_.html"><img src="../../../../../doc/html/images/prev.png" alt="Prev"></a><a accesskey="u" href="../index.html"><img src="../../../../../doc/html/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../../../doc/html/images/home.png" alt="Home"></a><a accesskey="n" href="type_requirements.html"><img src="../../../../../doc/html/images/next.png" alt="Next"></a>
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</body>
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|
||||
@ -1,11 +1,11 @@
|
||||
<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
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<meta name="generator" content="DocBook XSL Stylesheets V1.75.2">
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<link rel="home" href="../index.html" title="Chapter<EFBFBD>1.<2E>Boost.Optional">
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<meta name="generator" content="DocBook XSL Stylesheets V1.77.1">
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@ -13,16 +13,16 @@
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<table cellpadding="2" width="100%"><tr>
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<div class="section" title="Implementation Notes">
|
||||
<div class="section boost_optional_implementation_notes">
|
||||
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
|
||||
<a name="boost_optional.implementation_notes"></a><a class="link" href="implementation_notes.html" title="Implementation Notes">Implementation Notes</a>
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</h2></div></div></div>
|
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@ -41,7 +41,7 @@
|
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</div>
|
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<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
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<td align="left"></td>
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<td align="right"><div class="copyright-footer">Copyright <EFBFBD> 2003 -2007 Fernando Luis Cacciola Carballal<p>
|
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<td align="right"><div class="copyright-footer">Copyright © 2003-2007 Fernando Luis Cacciola Carballal<p>
|
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Distributed under the Boost Software License, Version 1.0. (See accompanying
|
||||
file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
|
||||
</p>
|
||||
@ -49,7 +49,7 @@
|
||||
</tr></table>
|
||||
<hr>
|
||||
<div class="spirit-nav">
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<a accesskey="p" href="type_requirements.html"><img src="../../../../../doc/html/images/prev.png" alt="Prev"></a><a accesskey="u" href="../index.html"><img src="../../../../../doc/html/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../../../doc/html/images/home.png" alt="Home"></a><a accesskey="n" href="dependencies_and_portability.html"><img src="../../../../../doc/html/images/next.png" alt="Next"></a>
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@ -13,16 +13,16 @@
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|
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<div class="section" title="In-Place Factories">
|
||||
<div class="section boost_optional_in_place_factories">
|
||||
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
|
||||
<a name="boost_optional.in_place_factories"></a><a class="link" href="in_place_factories.html" title="In-Place Factories">In-Place Factories</a>
|
||||
</h2></div></div></div>
|
||||
@ -36,7 +36,7 @@
|
||||
</p>
|
||||
<pre class="programlisting"><span class="keyword">struct</span> <span class="identifier">X</span>
|
||||
<span class="special">{</span>
|
||||
<span class="identifier">X</span> <span class="special">(</span> <span class="keyword">int</span><span class="special">,</span> <span class="identifier">std</span><span class="special">:::</span><span class="identifier">string</span> <span class="special">)</span> <span class="special">;</span>
|
||||
<span class="identifier">X</span> <span class="special">(</span> <span class="keyword">int</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span> <span class="special">)</span> <span class="special">;</span>
|
||||
<span class="special">}</span> <span class="special">;</span>
|
||||
|
||||
<span class="keyword">class</span> <span class="identifier">W</span>
|
||||
@ -50,8 +50,8 @@
|
||||
|
||||
<span class="keyword">void</span> <span class="identifier">foo</span><span class="special">()</span>
|
||||
<span class="special">{</span>
|
||||
<span class="comment">// Temporary object created.
|
||||
</span> <span class="identifier">W</span> <span class="special">(</span> <span class="identifier">X</span><span class="special">(</span><span class="number">123</span><span class="special">,</span><span class="string">"hello"</span><span class="special">)</span> <span class="special">)</span> <span class="special">;</span>
|
||||
<span class="comment">// Temporary object created.</span>
|
||||
<span class="identifier">W</span> <span class="special">(</span> <span class="identifier">X</span><span class="special">(</span><span class="number">123</span><span class="special">,</span><span class="string">"hello"</span><span class="special">)</span> <span class="special">)</span> <span class="special">;</span>
|
||||
<span class="special">}</span>
|
||||
</pre>
|
||||
<p>
|
||||
@ -71,9 +71,9 @@
|
||||
|
||||
<span class="keyword">void</span> <span class="identifier">foo</span><span class="special">()</span>
|
||||
<span class="special">{</span>
|
||||
<span class="comment">// Wrapped object constructed in-place
|
||||
</span> <span class="comment">// No temporary created.
|
||||
</span> <span class="identifier">W</span> <span class="special">(</span><span class="number">123</span><span class="special">,</span><span class="string">"hello"</span><span class="special">)</span> <span class="special">;</span>
|
||||
<span class="comment">// Wrapped object constructed in-place</span>
|
||||
<span class="comment">// No temporary created.</span>
|
||||
<span class="identifier">W</span> <span class="special">(</span><span class="number">123</span><span class="special">,</span><span class="string">"hello"</span><span class="special">)</span> <span class="special">;</span>
|
||||
<span class="special">}</span>
|
||||
</pre>
|
||||
<p>
|
||||
@ -119,24 +119,24 @@
|
||||
|
||||
<span class="keyword">void</span> <span class="identifier">foo</span><span class="special">()</span>
|
||||
<span class="special">{</span>
|
||||
<span class="comment">// Wrapped object constructed in-place via a TypedInPlaceFactory.
|
||||
</span> <span class="comment">// No temporary created.
|
||||
</span> <span class="identifier">W</span> <span class="special">(</span> <span class="identifier">TypedInPlaceFactory2</span><span class="special"><</span><span class="identifier">X</span><span class="special">,</span><span class="keyword">int</span><span class="special">,</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">>(</span><span class="number">123</span><span class="special">,</span><span class="string">"hello"</span><span class="special">))</span> <span class="special">;</span>
|
||||
<span class="comment">// Wrapped object constructed in-place via a TypedInPlaceFactory.</span>
|
||||
<span class="comment">// No temporary created.</span>
|
||||
<span class="identifier">W</span> <span class="special">(</span> <span class="identifier">TypedInPlaceFactory2</span><span class="special"><</span><span class="identifier">X</span><span class="special">,</span><span class="keyword">int</span><span class="special">,</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">>(</span><span class="number">123</span><span class="special">,</span><span class="string">"hello"</span><span class="special">))</span> <span class="special">;</span>
|
||||
<span class="special">}</span>
|
||||
</pre>
|
||||
<p>
|
||||
The factories are divided in two groups:
|
||||
</p>
|
||||
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
|
||||
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
|
||||
<li class="listitem">
|
||||
<span class="underline">TypedInPlaceFactories</span>: those which
|
||||
take the target type as a primary template parameter.
|
||||
</li>
|
||||
<span class="underline">TypedInPlaceFactories</span>: those which
|
||||
take the target type as a primary template parameter.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
<span class="underline">InPlaceFactories</span>: those with a template
|
||||
<code class="computeroutput"><span class="identifier">construct</span><span class="special">(</span><span class="keyword">void</span><span class="special">*)</span></code> member
|
||||
function taking the target type.
|
||||
</li>
|
||||
<span class="underline">InPlaceFactories</span>: those with a template
|
||||
<code class="computeroutput"><span class="identifier">construct</span><span class="special">(</span><span class="keyword">void</span><span class="special">*)</span></code> member
|
||||
function taking the target type.
|
||||
</li>
|
||||
</ul></div>
|
||||
<p>
|
||||
Within each group, all the family members differ only in the number of parameters
|
||||
@ -170,9 +170,9 @@
|
||||
|
||||
<span class="keyword">void</span> <span class="identifier">foo</span><span class="special">()</span>
|
||||
<span class="special">{</span>
|
||||
<span class="comment">// Wrapped object constructed in-place via a InPlaceFactory.
|
||||
</span> <span class="comment">// No temporary created.
|
||||
</span> <span class="identifier">W</span> <span class="special">(</span> <span class="identifier">in_place</span><span class="special">(</span><span class="number">123</span><span class="special">,</span><span class="string">"hello"</span><span class="special">)</span> <span class="special">)</span> <span class="special">;</span>
|
||||
<span class="comment">// Wrapped object constructed in-place via a InPlaceFactory.</span>
|
||||
<span class="comment">// No temporary created.</span>
|
||||
<span class="identifier">W</span> <span class="special">(</span> <span class="identifier">in_place</span><span class="special">(</span><span class="number">123</span><span class="special">,</span><span class="string">"hello"</span><span class="special">)</span> <span class="special">)</span> <span class="special">;</span>
|
||||
<span class="special">}</span>
|
||||
</pre>
|
||||
<p>
|
||||
@ -182,7 +182,7 @@
|
||||
</div>
|
||||
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
|
||||
<td align="left"></td>
|
||||
<td align="right"><div class="copyright-footer">Copyright <EFBFBD> 2003 -2007 Fernando Luis Cacciola Carballal<p>
|
||||
<td align="right"><div class="copyright-footer">Copyright © 2003-2007 Fernando Luis Cacciola Carballal<p>
|
||||
Distributed under the Boost Software License, Version 1.0. (See accompanying
|
||||
file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
|
||||
</p>
|
||||
@ -190,7 +190,7 @@
|
||||
</tr></table>
|
||||
<hr>
|
||||
<div class="spirit-nav">
|
||||
<a accesskey="p" href="rebinding_semantics_for_assignment_of_optional_references.html"><img src="../../../../../doc/html/images/prev.png" alt="Prev"></a><a accesskey="u" href="../index.html"><img src="../../../../../doc/html/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../../../doc/html/images/home.png" alt="Home"></a><a accesskey="n" href="a_note_about_optional_bool_.html"><img src="../../../../../doc/html/images/next.png" alt="Next"></a>
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|
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<link rel="stylesheet" href="../boostbook.css" type="text/css">
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|
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|
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@ -13,16 +13,16 @@
|
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<table cellpadding="2" width="100%"><tr>
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<a accesskey="p" href="examples.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../index.html"><img src="../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="rebinding_semantics_for_assignment_of_optional_references.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a>
|
||||
</div>
|
||||
<div class="section" title="Optional references">
|
||||
<div class="section boost_optional_optional_references">
|
||||
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
|
||||
<a name="boost_optional.optional_references"></a><a class="link" href="optional_references.html" title="Optional references">Optional references</a>
|
||||
</h2></div></div></div>
|
||||
@ -35,43 +35,43 @@
|
||||
However, since references are not real objects some restrictions apply and
|
||||
some operations are not available in this case:
|
||||
</p>
|
||||
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
|
||||
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
|
||||
<li class="listitem">
|
||||
Converting constructors
|
||||
</li>
|
||||
Converting constructors
|
||||
</li>
|
||||
<li class="listitem">
|
||||
Converting assignment
|
||||
</li>
|
||||
Converting assignment
|
||||
</li>
|
||||
<li class="listitem">
|
||||
InPlace construction
|
||||
</li>
|
||||
InPlace construction
|
||||
</li>
|
||||
<li class="listitem">
|
||||
InPlace assignment
|
||||
</li>
|
||||
InPlace assignment
|
||||
</li>
|
||||
<li class="listitem">
|
||||
Value-access via pointer
|
||||
</li>
|
||||
Value-access via pointer
|
||||
</li>
|
||||
</ul></div>
|
||||
<p>
|
||||
Also, even though <code class="computeroutput"><span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">&></span></code>
|
||||
treats it wrapped pseudo-object much as a real value, a true real reference
|
||||
is stored so aliasing will ocurr:
|
||||
</p>
|
||||
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
|
||||
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
|
||||
<li class="listitem">
|
||||
Copies of <code class="computeroutput"><span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">&></span></code>
|
||||
will copy the references but all these references will nonetheless reefer
|
||||
to the same object.
|
||||
</li>
|
||||
Copies of <code class="computeroutput"><span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">&></span></code>
|
||||
will copy the references but all these references will nonetheless reefer
|
||||
to the same object.
|
||||
</li>
|
||||
<li class="listitem">
|
||||
Value-access will actually provide access to the referenced object rather
|
||||
than the reference itself.
|
||||
</li>
|
||||
Value-access will actually provide access to the referenced object rather
|
||||
than the reference itself.
|
||||
</li>
|
||||
</ul></div>
|
||||
</div>
|
||||
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
|
||||
<td align="left"></td>
|
||||
<td align="right"><div class="copyright-footer">Copyright <EFBFBD> 2003 -2007 Fernando Luis Cacciola Carballal<p>
|
||||
<td align="right"><div class="copyright-footer">Copyright © 2003-2007 Fernando Luis Cacciola Carballal<p>
|
||||
Distributed under the Boost Software License, Version 1.0. (See accompanying
|
||||
file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
|
||||
</p>
|
||||
@ -79,7 +79,7 @@
|
||||
</tr></table>
|
||||
<hr>
|
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<div class="spirit-nav">
|
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<a accesskey="p" href="examples.html"><img src="../../../../../doc/html/images/prev.png" alt="Prev"></a><a accesskey="u" href="../index.html"><img src="../../../../../doc/html/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../../../doc/html/images/home.png" alt="Home"></a><a accesskey="n" href="rebinding_semantics_for_assignment_of_optional_references.html"><img src="../../../../../doc/html/images/next.png" alt="Next"></a>
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@ -1,11 +1,11 @@
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<link rel="prev" href="optional_references.html" title="Optional references">
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@ -13,16 +13,16 @@
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</div>
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||||
<div class="section" title="Rebinding semantics for assignment of optional references">
|
||||
<div class="section boost_optional_rebinding_semantics_for_assignment_of_optional_references">
|
||||
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
|
||||
<a name="boost_optional.rebinding_semantics_for_assignment_of_optional_references"></a><a class="link" href="rebinding_semantics_for_assignment_of_optional_references.html" title="Rebinding semantics for assignment of optional references">Rebinding
|
||||
semantics for assignment of optional references</a>
|
||||
@ -36,23 +36,23 @@
|
||||
<span class="keyword">int</span><span class="special">&</span> <span class="identifier">rx</span> <span class="special">=</span> <span class="identifier">x</span> <span class="special">;</span>
|
||||
<span class="identifier">optional</span><span class="special"><</span><span class="keyword">int</span><span class="special">&></span> <span class="identifier">ora</span> <span class="special">;</span>
|
||||
<span class="identifier">optional</span><span class="special"><</span><span class="keyword">int</span><span class="special">&></span> <span class="identifier">orb</span><span class="special">(</span><span class="identifier">x</span><span class="special">)</span> <span class="special">;</span>
|
||||
<span class="identifier">ora</span> <span class="special">=</span> <span class="identifier">orb</span> <span class="special">;</span> <span class="comment">// now 'ora' is bound to 'x' through 'rx'
|
||||
</span><span class="special">*</span><span class="identifier">ora</span> <span class="special">=</span> <span class="number">2</span> <span class="special">;</span> <span class="comment">// Changes value of 'x' through 'ora'
|
||||
</span><span class="identifier">assert</span><span class="special">(</span><span class="identifier">x</span><span class="special">==</span><span class="number">2</span><span class="special">);</span>
|
||||
<span class="identifier">ora</span> <span class="special">=</span> <span class="identifier">orb</span> <span class="special">;</span> <span class="comment">// now 'ora' is bound to 'x' through 'rx'</span>
|
||||
<span class="special">*</span><span class="identifier">ora</span> <span class="special">=</span> <span class="number">2</span> <span class="special">;</span> <span class="comment">// Changes value of 'x' through 'ora'</span>
|
||||
<span class="identifier">assert</span><span class="special">(</span><span class="identifier">x</span><span class="special">==</span><span class="number">2</span><span class="special">);</span>
|
||||
</pre>
|
||||
<p>
|
||||
If you assign to a bare C++ reference, the assignment is forwarded to the referenced
|
||||
object; it's value changes but the reference is never rebound.
|
||||
object; its value changes but the reference is never rebound.
|
||||
</p>
|
||||
<pre class="programlisting"><span class="keyword">int</span> <span class="identifier">a</span> <span class="special">=</span> <span class="number">1</span> <span class="special">;</span>
|
||||
<span class="keyword">int</span><span class="special">&</span> <span class="identifier">ra</span> <span class="special">=</span> <span class="identifier">a</span> <span class="special">;</span>
|
||||
<span class="keyword">int</span> <span class="identifier">b</span> <span class="special">=</span> <span class="number">2</span> <span class="special">;</span>
|
||||
<span class="keyword">int</span><span class="special">&</span> <span class="identifier">rb</span> <span class="special">=</span> <span class="identifier">b</span> <span class="special">;</span>
|
||||
<span class="identifier">ra</span> <span class="special">=</span> <span class="identifier">rb</span> <span class="special">;</span> <span class="comment">// Changes the value of 'a' to 'b'
|
||||
</span><span class="identifier">assert</span><span class="special">(</span><span class="identifier">a</span><span class="special">==</span><span class="identifier">b</span><span class="special">);</span>
|
||||
<span class="identifier">ra</span> <span class="special">=</span> <span class="identifier">rb</span> <span class="special">;</span> <span class="comment">// Changes the value of 'a' to 'b'</span>
|
||||
<span class="identifier">assert</span><span class="special">(</span><span class="identifier">a</span><span class="special">==</span><span class="identifier">b</span><span class="special">);</span>
|
||||
<span class="identifier">b</span> <span class="special">=</span> <span class="number">3</span> <span class="special">;</span>
|
||||
<span class="identifier">assert</span><span class="special">(</span><span class="identifier">ra</span><span class="special">!=</span><span class="identifier">b</span><span class="special">);</span> <span class="comment">// 'ra' is not rebound to 'b'
|
||||
</span></pre>
|
||||
<span class="identifier">assert</span><span class="special">(</span><span class="identifier">ra</span><span class="special">!=</span><span class="identifier">b</span><span class="special">);</span> <span class="comment">// 'ra' is not rebound to 'b'</span>
|
||||
</pre>
|
||||
<p>
|
||||
Now, if you assign to an <span class="emphasis"><em>initialized </em></span> <code class="computeroutput"><span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">&></span></code>,
|
||||
the effect is to <span class="bold"><strong>rebind</strong></span> to the new object
|
||||
@ -64,14 +64,14 @@
|
||||
<span class="keyword">int</span><span class="special">&</span> <span class="identifier">rb</span> <span class="special">=</span> <span class="identifier">b</span> <span class="special">;</span>
|
||||
<span class="identifier">optional</span><span class="special"><</span><span class="keyword">int</span><span class="special">&></span> <span class="identifier">ora</span><span class="special">(</span><span class="identifier">ra</span><span class="special">)</span> <span class="special">;</span>
|
||||
<span class="identifier">optional</span><span class="special"><</span><span class="keyword">int</span><span class="special">&></span> <span class="identifier">orb</span><span class="special">(</span><span class="identifier">rb</span><span class="special">)</span> <span class="special">;</span>
|
||||
<span class="identifier">ora</span> <span class="special">=</span> <span class="identifier">orb</span> <span class="special">;</span> <span class="comment">// 'ora' is rebound to 'b'
|
||||
</span><span class="special">*</span><span class="identifier">ora</span> <span class="special">=</span> <span class="number">3</span> <span class="special">;</span> <span class="comment">// Changes value of 'b' (not 'a')
|
||||
</span><span class="identifier">assert</span><span class="special">(</span><span class="identifier">a</span><span class="special">==</span><span class="number">1</span><span class="special">);</span>
|
||||
<span class="identifier">assert</span><span class="special">(</span><span class="identifier">b</span><span class="special">==</span><span class="number">3</span><span class="special">);</span>
|
||||
<span class="identifier">ora</span> <span class="special">=</span> <span class="identifier">orb</span> <span class="special">;</span> <span class="comment">// 'ora' is rebound to 'b'</span>
|
||||
<span class="special">*</span><span class="identifier">ora</span> <span class="special">=</span> <span class="number">3</span> <span class="special">;</span> <span class="comment">// Changes value of 'b' (not 'a')</span>
|
||||
<span class="identifier">assert</span><span class="special">(</span><span class="identifier">a</span><span class="special">==</span><span class="number">1</span><span class="special">);</span>
|
||||
<span class="identifier">assert</span><span class="special">(</span><span class="identifier">b</span><span class="special">==</span><span class="number">3</span><span class="special">);</span>
|
||||
</pre>
|
||||
<a name="boost_optional.rebinding_semantics_for_assignment_of_optional_references.rationale"></a><h4>
|
||||
<a name="id579234"></a>
|
||||
<a class="link" href="rebinding_semantics_for_assignment_of_optional_references.html#boost_optional.rebinding_semantics_for_assignment_of_optional_references.rationale">Rationale</a>
|
||||
<h4>
|
||||
<a name="boost_optional.rebinding_semantics_for_assignment_of_optional_references.h0"></a>
|
||||
<span class="phrase"><a name="boost_optional.rebinding_semantics_for_assignment_of_optional_references.rationale"></a></span><a class="link" href="rebinding_semantics_for_assignment_of_optional_references.html#boost_optional.rebinding_semantics_for_assignment_of_optional_references.rationale">Rationale</a>
|
||||
</h4>
|
||||
<p>
|
||||
Rebinding semantics for the assignment of <span class="emphasis"><em>initialized </em></span>
|
||||
@ -117,16 +117,16 @@
|
||||
or not.
|
||||
</p>
|
||||
<p>
|
||||
That is, you would have to discriminate in order to be consistency.
|
||||
That is, you would have to discriminate in order to be consistent.
|
||||
</p>
|
||||
<p>
|
||||
If in your code rebinding to another object is not an option, then is very
|
||||
likely that binding for the fist time isn't either. In such case, assignment
|
||||
If in your code rebinding to another object is not an option, then it is very
|
||||
likely that binding for the first time isn't either. In such case, assignment
|
||||
to an <span class="emphasis"><em>uninitialized </em></span> <code class="computeroutput"><span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">&></span></code>
|
||||
shall be prohibited. It is quite possible that in such scenario the precondition
|
||||
that the lvalue must be already initialized exist. If it doesn't, then binding
|
||||
for the first time is OK while rebinding is not which is IMO very unlikely.
|
||||
In such scenario, you can assign the value itself directly, as in:
|
||||
shall be prohibited. It is quite possible that in such a scenario it is a precondition
|
||||
that the lvalue must be already initialized. If it isn't, then binding for
|
||||
the first time is OK while rebinding is not which is IMO very unlikely. In
|
||||
such a scenario, you can assign the value itself directly, as in:
|
||||
</p>
|
||||
<pre class="programlisting"><span class="identifier">assert</span><span class="special">(!!</span><span class="identifier">opt</span><span class="special">);</span>
|
||||
<span class="special">*</span><span class="identifier">opt</span><span class="special">=</span><span class="identifier">value</span><span class="special">;</span>
|
||||
@ -134,7 +134,7 @@
|
||||
</div>
|
||||
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
|
||||
<td align="left"></td>
|
||||
<td align="right"><div class="copyright-footer">Copyright <EFBFBD> 2003 -2007 Fernando Luis Cacciola Carballal<p>
|
||||
<td align="right"><div class="copyright-footer">Copyright © 2003-2007 Fernando Luis Cacciola Carballal<p>
|
||||
Distributed under the Boost Software License, Version 1.0. (See accompanying
|
||||
file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
|
||||
</p>
|
||||
@ -142,7 +142,7 @@
|
||||
</tr></table>
|
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@ -1,11 +1,11 @@
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|
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@ -13,36 +13,38 @@
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|
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<div class="section" title="Synopsis">
|
||||
<div class="section boost_optional_synopsis">
|
||||
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
|
||||
<a name="boost_optional.synopsis"></a><a class="link" href="synopsis.html" title="Synopsis">Synopsis</a>
|
||||
</h2></div></div></div>
|
||||
<pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">boost</span> <span class="special">{</span>
|
||||
<pre class="programlisting"><code class="computeroutput"><span class="comment">// In Header: <</span></code><a href="../../../../../boost/optional/optional.hpp" target="_top">boost/optional/optional.hpp</a><span class="comment">></span>
|
||||
|
||||
<span class="keyword">namespace</span> <span class="identifier">boost</span> <span class="special">{</span>
|
||||
|
||||
<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">></span>
|
||||
<span class="keyword">class</span> <span class="identifier">optional</span>
|
||||
<span class="special">{</span>
|
||||
<span class="keyword">public</span> <span class="special">:</span>
|
||||
|
||||
<span class="comment">// (If T is of reference type, the parameters and results by reference are by value)
|
||||
</span>
|
||||
<span class="comment">// (If T is of reference type, the parameters and results by reference are by value)</span>
|
||||
|
||||
<span class="identifier">optional</span> <span class="special">()</span> <span class="special">;</span> <a class="link" href="detailed_semantics.html#reference_optional_constructor"><span class="inlinemediaobject"><img src="../images/callouts/R.png" alt="R"></span></a>
|
||||
|
||||
<span class="identifier">optional</span> <span class="special">(</span> <span class="identifier">none_t</span> <span class="special">)</span> <span class="special">;</span> <a class="link" href="detailed_semantics.html#reference_optional_constructor_none_t"><span class="inlinemediaobject"><img src="../images/callouts/R.png" alt="R"></span></a>
|
||||
|
||||
<span class="identifier">optional</span> <span class="special">(</span> <span class="identifier">T</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">v</span> <span class="special">)</span> <span class="special">;</span> <a class="link" href="detailed_semantics.html#reference_optional_constructor_value"><span class="inlinemediaobject"><img src="../images/callouts/R.png" alt="R"></span></a>
|
||||
|
||||
<span class="comment">// [new in 1.34]
|
||||
</span> <span class="identifier">optional</span> <span class="special">(</span> <span class="keyword">bool</span> <span class="identifier">condition</span><span class="special">,</span> <span class="identifier">T</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">v</span> <span class="special">)</span> <span class="special">;</span> <a class="link" href="detailed_semantics.html#reference_optional_constructor_bool_value"><span class="inlinemediaobject"><img src="../images/callouts/R.png" alt="R"></span></a>
|
||||
<span class="comment">// [new in 1.34]</span>
|
||||
<span class="identifier">optional</span> <span class="special">(</span> <span class="keyword">bool</span> <span class="identifier">condition</span><span class="special">,</span> <span class="identifier">T</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">v</span> <span class="special">)</span> <span class="special">;</span> <a class="link" href="detailed_semantics.html#reference_optional_constructor_bool_value"><span class="inlinemediaobject"><img src="../images/callouts/R.png" alt="R"></span></a>
|
||||
|
||||
<span class="identifier">optional</span> <span class="special">(</span> <span class="identifier">optional</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">rhs</span> <span class="special">)</span> <span class="special">;</span> <a class="link" href="detailed_semantics.html#reference_optional_constructor_optional"><span class="inlinemediaobject"><img src="../images/callouts/R.png" alt="R"></span></a>
|
||||
|
||||
@ -52,7 +54,7 @@
|
||||
|
||||
<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">TypedInPlaceFactory</span><span class="special">></span> <span class="keyword">explicit</span> <span class="identifier">optional</span> <span class="special">(</span> <span class="identifier">TypedInPlaceFactory</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">f</span> <span class="special">)</span> <span class="special">;</span> <a class="link" href="detailed_semantics.html#reference_optional_constructor_factory"><span class="inlinemediaobject"><img src="../images/callouts/R.png" alt="R"></span></a>
|
||||
|
||||
<span class="identifier">optional</span><span class="special">&</span> <span class="keyword">operator</span> <span class="special">=</span> <span class="special">(</span> <span class="identifier">none_t</span> <span class="special">)</span> <span class="special">;</span>
|
||||
<span class="identifier">optional</span><span class="special">&</span> <span class="keyword">operator</span> <span class="special">=</span> <span class="special">(</span> <span class="identifier">none_t</span> <span class="special">)</span> <span class="special">;</span>
|
||||
|
||||
<span class="identifier">optional</span><span class="special">&</span> <span class="keyword">operator</span> <span class="special">=</span> <span class="special">(</span> <span class="identifier">T</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">v</span> <span class="special">)</span> <span class="special">;</span> <a class="link" href="detailed_semantics.html#reference_optional_operator_equal_value"><span class="inlinemediaobject"><img src="../images/callouts/R.png" alt="R"></span></a>
|
||||
|
||||
@ -60,15 +62,15 @@
|
||||
|
||||
<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">U</span><span class="special">></span> <span class="identifier">optional</span><span class="special">&</span> <span class="keyword">operator</span> <span class="special">=</span> <span class="special">(</span> <span class="identifier">optional</span><span class="special"><</span><span class="identifier">U</span><span class="special">></span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">rhs</span> <span class="special">)</span> <span class="special">;</span> <a class="link" href="detailed_semantics.html#reference_optional_operator_equal_other_optional"><span class="inlinemediaobject"><img src="../images/callouts/R.png" alt="R"></span></a>
|
||||
|
||||
<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">InPlaceFactory</span><span class="special">></span> <span class="identifier">optional</span><span class="special">&</span> <span class="keyword">operator</span> <span class="special">=</span> <span class="special">(</span> <span class="identifier">InPlaceFactory</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">f</span> <span class="special">)</span> <span class="special">;</span>
|
||||
<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">InPlaceFactory</span><span class="special">></span> <span class="identifier">optional</span><span class="special">&</span> <span class="keyword">operator</span> <span class="special">=</span> <span class="special">(</span> <span class="identifier">InPlaceFactory</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">f</span> <span class="special">)</span> <span class="special">;</span> <a class="link" href="detailed_semantics.html#reference_optional_operator_equal_factory"><span class="inlinemediaobject"><img src="../images/callouts/R.png" alt="R"></span></a>
|
||||
|
||||
<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">TypedInPlaceFactory</span><span class="special">></span> <span class="identifier">optional</span><span class="special">&</span> <span class="keyword">operator</span> <span class="special">=</span> <span class="special">(</span> <span class="identifier">TypedInPlaceFactory</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">f</span> <span class="special">)</span> <span class="special">;</span>
|
||||
<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">TypedInPlaceFactory</span><span class="special">></span> <span class="identifier">optional</span><span class="special">&</span> <span class="keyword">operator</span> <span class="special">=</span> <span class="special">(</span> <span class="identifier">TypedInPlaceFactory</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">f</span> <span class="special">)</span> <span class="special">;</span> <a class="link" href="detailed_semantics.html#reference_optional_operator_equal_factory"><span class="inlinemediaobject"><img src="../images/callouts/R.png" alt="R"></span></a>
|
||||
|
||||
<span class="identifier">T</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">get</span><span class="special">()</span> <span class="keyword">const</span> <span class="special">;</span> <a class="link" href="detailed_semantics.html#reference_optional_get"><span class="inlinemediaobject"><img src="../images/callouts/R.png" alt="R"></span></a>
|
||||
<span class="identifier">T</span><span class="special">&</span> <span class="identifier">get</span><span class="special">()</span> <span class="special">;</span> <a class="link" href="detailed_semantics.html#reference_optional_get"><span class="inlinemediaobject"><img src="../images/callouts/R.png" alt="R"></span></a>
|
||||
|
||||
<span class="comment">// [new in 1.34]
|
||||
</span> <span class="identifier">T</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">get_value_or</span><span class="special">(</span> <span class="identifier">T</span> <span class="keyword">const</span><span class="special">&</span> <span class="keyword">default</span> <span class="special">)</span> <span class="keyword">const</span> <span class="special">;</span> <a class="link" href="detailed_semantics.html#reference_optional_get_value_or_value"><span class="inlinemediaobject"><img src="../images/callouts/R.png" alt="R"></span></a>
|
||||
<span class="comment">// [new in 1.34]</span>
|
||||
<span class="identifier">T</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">get_value_or</span><span class="special">(</span> <span class="identifier">T</span> <span class="keyword">const</span><span class="special">&</span> <span class="keyword">default</span> <span class="special">)</span> <span class="keyword">const</span> <span class="special">;</span> <a class="link" href="detailed_semantics.html#reference_optional_get_value_or_value"><span class="inlinemediaobject"><img src="../images/callouts/R.png" alt="R"></span></a>
|
||||
|
||||
<span class="identifier">T</span> <span class="keyword">const</span><span class="special">*</span> <span class="keyword">operator</span> <span class="special">->()</span> <span class="keyword">const</span> <span class="special">;</span> <a class="link" href="detailed_semantics.html#reference_optional_operator_arrow"><span class="inlinemediaobject"><img src="../images/callouts/R.png" alt="R"></span></a>
|
||||
<span class="identifier">T</span><span class="special">*</span> <span class="keyword">operator</span> <span class="special">->()</span> <span class="special">;</span> <a class="link" href="detailed_semantics.html#reference_optional_operator_arrow"><span class="inlinemediaobject"><img src="../images/callouts/R.png" alt="R"></span></a>
|
||||
@ -83,16 +85,16 @@
|
||||
|
||||
<span class="keyword">bool</span> <span class="keyword">operator</span><span class="special">!()</span> <span class="keyword">const</span> <span class="special">;</span> <a class="link" href="detailed_semantics.html#reference_optional_operator_not"><span class="inlinemediaobject"><img src="../images/callouts/R.png" alt="R"></span></a>
|
||||
|
||||
<span class="comment">// deprecated methods
|
||||
</span>
|
||||
<span class="comment">// (deprecated)
|
||||
</span> <span class="keyword">void</span> <span class="identifier">reset</span><span class="special">()</span> <span class="special">;</span> <a class="link" href="detailed_semantics.html#reference_optional_reset"><span class="inlinemediaobject"><img src="../images/callouts/R.png" alt="R"></span></a>
|
||||
<span class="comment">// deprecated methods</span>
|
||||
|
||||
<span class="comment">// (deprecated)
|
||||
</span> <span class="keyword">void</span> <span class="identifier">reset</span> <span class="special">(</span> <span class="identifier">T</span> <span class="keyword">const</span><span class="special">&</span> <span class="special">)</span> <span class="special">;</span> <a class="link" href="detailed_semantics.html#reference_optional_reset_value"><span class="inlinemediaobject"><img src="../images/callouts/R.png" alt="R"></span></a>
|
||||
<span class="comment">// (deprecated)</span>
|
||||
<span class="keyword">void</span> <span class="identifier">reset</span><span class="special">()</span> <span class="special">;</span> <a class="link" href="detailed_semantics.html#reference_optional_reset"><span class="inlinemediaobject"><img src="../images/callouts/R.png" alt="R"></span></a>
|
||||
|
||||
<span class="comment">// (deprecated)
|
||||
</span> <span class="keyword">bool</span> <span class="identifier">is_initialized</span><span class="special">()</span> <span class="keyword">const</span> <span class="special">;</span> <a class="link" href="detailed_semantics.html#reference_optional_is_initialized"><span class="inlinemediaobject"><img src="../images/callouts/R.png" alt="R"></span></a>
|
||||
<span class="comment">// (deprecated)</span>
|
||||
<span class="keyword">void</span> <span class="identifier">reset</span> <span class="special">(</span> <span class="identifier">T</span> <span class="keyword">const</span><span class="special">&</span> <span class="special">)</span> <span class="special">;</span> <a class="link" href="detailed_semantics.html#reference_optional_reset_value"><span class="inlinemediaobject"><img src="../images/callouts/R.png" alt="R"></span></a>
|
||||
|
||||
<span class="comment">// (deprecated)</span>
|
||||
<span class="keyword">bool</span> <span class="identifier">is_initialized</span><span class="special">()</span> <span class="keyword">const</span> <span class="special">;</span> <a class="link" href="detailed_semantics.html#reference_optional_is_initialized"><span class="inlinemediaobject"><img src="../images/callouts/R.png" alt="R"></span></a>
|
||||
|
||||
<span class="special">};</span>
|
||||
|
||||
@ -108,14 +110,14 @@
|
||||
|
||||
<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">></span> <span class="keyword">inline</span> <span class="keyword">bool</span> <span class="keyword">operator</span> <span class="special">>=</span> <span class="special">(</span> <span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">></span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">x</span><span class="special">,</span> <span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">></span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">y</span> <span class="special">)</span> <span class="special">;</span> <a class="link" href="detailed_semantics.html#reference_operator_compare_greater_or_equal_optional_optional"><span class="inlinemediaobject"><img src="../images/callouts/R.png" alt="R"></span></a>
|
||||
|
||||
<span class="comment">// [new in 1.34]
|
||||
</span><span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">></span> <span class="keyword">inline</span> <span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">></span> <span class="identifier">make_optional</span> <span class="special">(</span> <span class="identifier">T</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">v</span> <span class="special">)</span> <span class="special">;</span> <a class="link" href="detailed_semantics.html#reference_make_optional_value"><span class="inlinemediaobject"><img src="../images/callouts/R.png" alt="R"></span></a>
|
||||
<span class="comment">// [new in 1.34]</span>
|
||||
<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">></span> <span class="keyword">inline</span> <span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">></span> <span class="identifier">make_optional</span> <span class="special">(</span> <span class="identifier">T</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">v</span> <span class="special">)</span> <span class="special">;</span> <a class="link" href="detailed_semantics.html#reference_make_optional_value"><span class="inlinemediaobject"><img src="../images/callouts/R.png" alt="R"></span></a>
|
||||
|
||||
<span class="comment">// [new in 1.34]
|
||||
</span><span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">></span> <span class="keyword">inline</span> <span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">></span> <span class="identifier">make_optional</span> <span class="special">(</span> <span class="keyword">bool</span> <span class="identifier">condition</span><span class="special">,</span> <span class="identifier">T</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">v</span> <span class="special">)</span> <span class="special">;</span> <a class="link" href="detailed_semantics.html#reference_make_optional_bool_value"><span class="inlinemediaobject"><img src="../images/callouts/R.png" alt="R"></span></a>
|
||||
<span class="comment">// [new in 1.34]</span>
|
||||
<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">></span> <span class="keyword">inline</span> <span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">></span> <span class="identifier">make_optional</span> <span class="special">(</span> <span class="keyword">bool</span> <span class="identifier">condition</span><span class="special">,</span> <span class="identifier">T</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">v</span> <span class="special">)</span> <span class="special">;</span> <a class="link" href="detailed_semantics.html#reference_make_optional_bool_value"><span class="inlinemediaobject"><img src="../images/callouts/R.png" alt="R"></span></a>
|
||||
|
||||
<span class="comment">// [new in 1.34]
|
||||
</span><span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">></span> <span class="keyword">inline</span> <span class="identifier">T</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">get_optional_value_or</span> <span class="special">(</span> <span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">></span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">opt</span><span class="special">,</span> <span class="identifier">T</span> <span class="keyword">const</span><span class="special">&</span> <span class="keyword">default</span> <span class="special">)</span> <span class="special">;</span> <a class="link" href="detailed_semantics.html#reference_optional_get_value_or_value"><span class="inlinemediaobject"><img src="../images/callouts/R.png" alt="R"></span></a>
|
||||
<span class="comment">// [new in 1.34]</span>
|
||||
<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">></span> <span class="keyword">inline</span> <span class="identifier">T</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">get_optional_value_or</span> <span class="special">(</span> <span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">></span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">opt</span><span class="special">,</span> <span class="identifier">T</span> <span class="keyword">const</span><span class="special">&</span> <span class="keyword">default</span> <span class="special">)</span> <span class="special">;</span> <a class="link" href="detailed_semantics.html#reference_optional_get_value_or_value"><span class="inlinemediaobject"><img src="../images/callouts/R.png" alt="R"></span></a>
|
||||
|
||||
<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">></span> <span class="keyword">inline</span> <span class="identifier">T</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">get</span> <span class="special">(</span> <span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">></span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">opt</span> <span class="special">)</span> <span class="special">;</span> <a class="link" href="detailed_semantics.html#reference_optional_get"><span class="inlinemediaobject"><img src="../images/callouts/R.png" alt="R"></span></a>
|
||||
|
||||
@ -131,12 +133,12 @@
|
||||
|
||||
<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">></span> <span class="keyword">inline</span> <span class="keyword">void</span> <span class="identifier">swap</span><span class="special">(</span> <span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">>&</span> <span class="identifier">x</span><span class="special">,</span> <span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">>&</span> <span class="identifier">y</span> <span class="special">)</span> <span class="special">;</span> <a class="link" href="detailed_semantics.html#reference_swap_optional_optional"><span class="inlinemediaobject"><img src="../images/callouts/R.png" alt="R"></span></a>
|
||||
|
||||
<span class="special">}</span> <span class="comment">// namespace boost
|
||||
</span></pre>
|
||||
<span class="special">}</span> <span class="comment">// namespace boost</span>
|
||||
</pre>
|
||||
</div>
|
||||
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
|
||||
<td align="left"></td>
|
||||
<td align="right"><div class="copyright-footer">Copyright <EFBFBD> 2003 -2007 Fernando Luis Cacciola Carballal<p>
|
||||
<td align="right"><div class="copyright-footer">Copyright © 2003-2007 Fernando Luis Cacciola Carballal<p>
|
||||
Distributed under the Boost Software License, Version 1.0. (See accompanying
|
||||
file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
|
||||
</p>
|
||||
@ -144,7 +146,7 @@
|
||||
</tr></table>
|
||||
<hr>
|
||||
<div class="spirit-nav">
|
||||
<a accesskey="p" href="development.html"><img src="../../../../../doc/html/images/prev.png" alt="Prev"></a><a accesskey="u" href="../index.html"><img src="../../../../../doc/html/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../../../doc/html/images/home.png" alt="Home"></a><a accesskey="n" href="detailed_semantics.html"><img src="../../../../../doc/html/images/next.png" alt="Next"></a>
|
||||
<a accesskey="p" href="development.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../index.html"><img src="../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="detailed_semantics.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
|
||||
@ -1,11 +1,11 @@
|
||||
<html>
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=US-ASCII">
|
||||
<title>Type requirements</title>
|
||||
<link rel="stylesheet" href="../boostbook.css" type="text/css">
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.75.2">
|
||||
<link rel="home" href="../index.html" title="Chapter<EFBFBD>1.<2E>Boost.Optional">
|
||||
<link rel="up" href="../index.html" title="Chapter<EFBFBD>1.<2E>Boost.Optional">
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.77.1">
|
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<link rel="home" href="../index.html" title="Chapter 1. Boost.Optional">
|
||||
<link rel="up" href="../index.html" title="Chapter 1. Boost.Optional">
|
||||
<link rel="prev" href="exception_safety_guarantees.html" title="Exception Safety Guarantees">
|
||||
<link rel="next" href="implementation_notes.html" title="Implementation Notes">
|
||||
</head>
|
||||
@ -13,16 +13,16 @@
|
||||
<table cellpadding="2" width="100%"><tr>
|
||||
<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../boost.png"></td>
|
||||
<td align="center"><a href="../../../../../index.html">Home</a></td>
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<td align="center"><a href="../../../../libraries.htm">Libraries</a></td>
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<td align="center"><a href="../../../../../libs/libraries.htm">Libraries</a></td>
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<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td>
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<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td>
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<a accesskey="p" href="exception_safety_guarantees.html"><img src="../../../../../doc/html/images/prev.png" alt="Prev"></a><a accesskey="u" href="../index.html"><img src="../../../../../doc/html/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../../../doc/html/images/home.png" alt="Home"></a><a accesskey="n" href="implementation_notes.html"><img src="../../../../../doc/html/images/next.png" alt="Next"></a>
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<a accesskey="p" href="exception_safety_guarantees.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../index.html"><img src="../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="implementation_notes.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a>
|
||||
</div>
|
||||
<div class="section" title="Type requirements">
|
||||
<div class="section boost_optional_type_requirements">
|
||||
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
|
||||
<a name="boost_optional.type_requirements"></a><a class="link" href="type_requirements.html" title="Type requirements">Type requirements</a>
|
||||
</h2></div></div></div>
|
||||
@ -39,7 +39,7 @@
|
||||
</div>
|
||||
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
|
||||
<td align="left"></td>
|
||||
<td align="right"><div class="copyright-footer">Copyright <EFBFBD> 2003 -2007 Fernando Luis Cacciola Carballal<p>
|
||||
<td align="right"><div class="copyright-footer">Copyright © 2003-2007 Fernando Luis Cacciola Carballal<p>
|
||||
Distributed under the Boost Software License, Version 1.0. (See accompanying
|
||||
file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
|
||||
</p>
|
||||
@ -47,7 +47,7 @@
|
||||
</tr></table>
|
||||
<hr>
|
||||
<div class="spirit-nav">
|
||||
<a accesskey="p" href="exception_safety_guarantees.html"><img src="../../../../../doc/html/images/prev.png" alt="Prev"></a><a accesskey="u" href="../index.html"><img src="../../../../../doc/html/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../../../doc/html/images/home.png" alt="Home"></a><a accesskey="n" href="implementation_notes.html"><img src="../../../../../doc/html/images/next.png" alt="Next"></a>
|
||||
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|
||||
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|
||||
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|
||||
</html>
|
||||
|
||||
0
doc/html/boostbook.css
Executable file → Normal file
0
doc/html/boostbook.css
Executable file → Normal file
@ -1,33 +1,33 @@
|
||||
<html>
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
|
||||
<title>Chapter<EFBFBD>1.<2E>Boost.Optional</title>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=US-ASCII">
|
||||
<title>Chapter 1. Boost.Optional</title>
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<link rel="stylesheet" href="boostbook.css" type="text/css">
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<meta name="generator" content="DocBook XSL Stylesheets V1.75.2">
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<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
|
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<table cellpadding="2" width="100%"><tr>
|
||||
<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../boost.png"></td>
|
||||
<td align="center"><a href="../../../../index.html">Home</a></td>
|
||||
<td align="center"><a href="../../../libraries.htm">Libraries</a></td>
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<td align="center"><a href="../../../../libs/libraries.htm">Libraries</a></td>
|
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<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td>
|
||||
<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td>
|
||||
<td align="center"><a href="../../../../more/index.htm">More</a></td>
|
||||
</tr></table>
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<hr>
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<div class="chapter" title="Chapter<65>1.<2E>Boost.Optional">
|
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<div class="spirit-nav"><a accesskey="n" href="boost_optional/development.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a></div>
|
||||
<div class="chapter">
|
||||
<div class="titlepage"><div>
|
||||
<div><h2 class="title">
|
||||
<a name="optional"></a>Chapter<EFBFBD>1.<2E>Boost.Optional</h2></div>
|
||||
<a name="optional"></a>Chapter 1. Boost.Optional</h2></div>
|
||||
<div><div class="author"><h3 class="author">
|
||||
<span class="firstname">Fernando Luis</span> <span class="surname">Cacciola Carballal</span>
|
||||
</h3></div></div>
|
||||
<div><p class="copyright">Copyright <EFBFBD> 2003 -2007 Fernando Luis Cacciola Carballal</p></div>
|
||||
<div><div class="legalnotice" title="Legal Notice">
|
||||
<a name="id553943"></a><p>
|
||||
<div><p class="copyright">Copyright © 2003-2007 Fernando Luis Cacciola Carballal</p></div>
|
||||
<div><div class="legalnotice">
|
||||
<a name="optional.legal"></a><p>
|
||||
Distributed under the Boost Software License, Version 1.0. (See accompanying
|
||||
file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
|
||||
</p>
|
||||
@ -71,7 +71,7 @@
|
||||
<dt><span class="section"><a href="boost_optional/acknowledgments.html">Acknowledgments</a></span></dt>
|
||||
</dl>
|
||||
</div>
|
||||
<div class="section" title="Motivation">
|
||||
<div class="section optional_motivation">
|
||||
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
|
||||
<a name="optional.motivation"></a><a class="link" href="index.html#optional.motivation" title="Motivation">Motivation</a>
|
||||
</h2></div></div></div>
|
||||
@ -79,17 +79,16 @@
|
||||
Consider these functions which should return a value but which might not have
|
||||
a value to return:
|
||||
</p>
|
||||
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
|
||||
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
|
||||
<li class="listitem">
|
||||
(A) <code class="computeroutput"><span class="keyword">double</span> <span class="identifier">sqrt</span><span class="special">(</span><span class="keyword">double</span> <span class="identifier">n</span>
|
||||
<span class="special">);</span></code>
|
||||
</li>
|
||||
(A) <code class="computeroutput"><span class="keyword">double</span> <span class="identifier">sqrt</span><span class="special">(</span><span class="keyword">double</span> <span class="identifier">n</span> <span class="special">);</span></code>
|
||||
</li>
|
||||
<li class="listitem">
|
||||
(B) <code class="computeroutput"><span class="keyword">char</span> <span class="identifier">get_async_input</span><span class="special">();</span></code>
|
||||
</li>
|
||||
(B) <code class="computeroutput"><span class="keyword">char</span> <span class="identifier">get_async_input</span><span class="special">();</span></code>
|
||||
</li>
|
||||
<li class="listitem">
|
||||
(C) <code class="computeroutput"><span class="identifier">point</span> <span class="identifier">polygon</span><span class="special">::</span><span class="identifier">get_any_point_effectively_inside</span><span class="special">();</span></code>
|
||||
</li>
|
||||
(C) <code class="computeroutput"><span class="identifier">point</span> <span class="identifier">polygon</span><span class="special">::</span><span class="identifier">get_any_point_effectively_inside</span><span class="special">();</span></code>
|
||||
</li>
|
||||
</ul></div>
|
||||
<p>
|
||||
There are different approaches to the issue of not having a value to return.
|
||||
@ -146,7 +145,7 @@
|
||||
<span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special"><</span><span class="identifier">point</span><span class="special">,</span><span class="keyword">bool</span><span class="special">></span> <span class="identifier">polygon</span><span class="special">::</span><span class="identifier">get_any_point_effectively_inside</span><span class="special">();</span>
|
||||
</pre>
|
||||
<p>
|
||||
These functions use a consistent interface for dealing with possibly inexistent
|
||||
These functions use a consistent interface for dealing with possibly nonexistent
|
||||
results:
|
||||
</p>
|
||||
<pre class="programlisting"><span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special"><</span><span class="identifier">point</span><span class="special">,</span><span class="keyword">bool</span><span class="special">></span> <span class="identifier">p</span> <span class="special">=</span> <span class="identifier">poly</span><span class="special">.</span><span class="identifier">get_any_point_effectively_inside</span><span class="special">();</span>
|
||||
@ -162,14 +161,12 @@
|
||||
Clearly, we need a better idiom.
|
||||
</p>
|
||||
</div>
|
||||
<p>
|
||||
</p>
|
||||
</div>
|
||||
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
|
||||
<td align="left"><p><small>Last revised: November 20, 2009 at 10:24:28 GMT</small></p></td>
|
||||
<td align="left"><p><small>Last revised: February 16, 2013 at 19:42:23 GMT</small></p></td>
|
||||
<td align="right"><div class="copyright-footer"></div></td>
|
||||
</tr></table>
|
||||
<hr>
|
||||
<div class="spirit-nav"><a accesskey="n" href="boost_optional/development.html"><img src="../../../../doc/html/images/next.png" alt="Next"></a></div>
|
||||
<div class="spirit-nav"><a accesskey="n" href="boost_optional/development.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a></div>
|
||||
</body>
|
||||
</html>
|
||||
|
||||
@ -99,7 +99,7 @@ functions could have the following interface:
|
||||
std::pair<char,bool> get_async_input();
|
||||
std::pair<point,bool> polygon::get_any_point_effectively_inside();
|
||||
|
||||
These functions use a consistent interface for dealing with possibly inexistent
|
||||
These functions use a consistent interface for dealing with possibly nonexistent
|
||||
results:
|
||||
|
||||
std::pair<point,bool> p = poly.get_any_point_effectively_inside();
|
||||
|
||||
@ -11,6 +11,8 @@
|
||||
|
||||
[section Synopsis]
|
||||
|
||||
```// In Header: <`[@boost:/boost/optional/optional.hpp boost/optional/optional.hpp]'''<phrase role="comment">></phrase>'''``
|
||||
|
||||
namespace boost {
|
||||
|
||||
template<class T>
|
||||
@ -45,9 +47,9 @@
|
||||
|
||||
template<class U> optional& operator = ( optional<U> const& rhs ) ; ``[link reference_optional_operator_equal_other_optional __GO_TO__]``
|
||||
|
||||
template<class InPlaceFactory> optional& operator = ( InPlaceFactory const& f ) ; ``[/[link reference_optional_operator_equal_factory __GO_TO__]]``
|
||||
template<class InPlaceFactory> optional& operator = ( InPlaceFactory const& f ) ; ``[link reference_optional_operator_equal_factory __GO_TO__]``
|
||||
|
||||
template<class TypedInPlaceFactory> optional& operator = ( TypedInPlaceFactory const& f ) ; ``[/[link reference_optional_operator_equal_factory __GO_TO__]]``
|
||||
template<class TypedInPlaceFactory> optional& operator = ( TypedInPlaceFactory const& f ) ; ``[link reference_optional_operator_equal_factory __GO_TO__]``
|
||||
|
||||
T const& get() const ; ``[link reference_optional_get __GO_TO__]``
|
||||
T& get() ; ``[link reference_optional_get __GO_TO__]``
|
||||
@ -232,7 +234,7 @@ __SPACE__
|
||||
|
||||
* otherwise, same as:
|
||||
|
||||
[: `optional<T ['(not a ref)]>::optional()`]
|
||||
[: `optional<T `['(not a ref)]`>::optional()`]
|
||||
[: `optional<T&> ::optional()`]
|
||||
|
||||
__SPACE__
|
||||
@ -379,12 +381,12 @@ assert ( *opt == y ) ;
|
||||
|
||||
__SPACE__
|
||||
|
||||
[: `optional<T&>& optional<T&>::operator= ( T& const& rhs ) ;`]
|
||||
[: `optional<T&>& optional<T&>::operator= ( T& rhs ) ;`]
|
||||
|
||||
* [*Effect:] (Re)binds thee wrapped reference.
|
||||
* [*Effect:] (Re)binds the wrapped reference.
|
||||
* [*Postconditions: ] `*this` is initialized and it references the same
|
||||
object referenced by `rhs`.
|
||||
* [*Notes:] If `*this` was initialized, is is ['rebound] to the new object.
|
||||
* [*Notes:] If `*this` was initialized, it is ['rebound] to the new object.
|
||||
See [link boost_optional.rebinding_semantics_for_assignment_of_optional_references here] for details on this behavior.
|
||||
* [*Example:]
|
||||
``
|
||||
@ -443,7 +445,7 @@ __SPACE__
|
||||
* [*Postconditions:] If `*rhs` is initialized, `*this` is initialized and it
|
||||
references the same object referenced by `*rhs`; otherwise, `*this` is
|
||||
uninitialized (and references no object).
|
||||
* [*Notes:] If `*this` was initialized and so is *rhs, this is is ['rebound] to
|
||||
* [*Notes:] If `*this` was initialized and so is `*rhs`, `*this` is ['rebound] to
|
||||
the new object. See [link boost_optional.rebinding_semantics_for_assignment_of_optional_references here] for details on this behavior.
|
||||
* [*Example:]
|
||||
``
|
||||
@ -500,6 +502,23 @@ assert ( *opt1 == static_cast<U>(v) ) ;
|
||||
|
||||
__SPACE__
|
||||
|
||||
[#reference_optional_operator_equal_factory]
|
||||
|
||||
[: `template<InPlaceFactory> optional<T>& optional<T` ['(not a ref)]`>::operator=( InPlaceFactory const& f );`]
|
||||
[: `template<TypedInPlaceFactory> optional<T>& optional<T` ['(not a ref)]`>::operator=( TypedInPlaceFactory const& f );`]
|
||||
|
||||
* [*Effect:] Assigns an `optional` with a value of `T` obtained from the
|
||||
factory.
|
||||
* [*Postconditions: ] `*this` is [_initialized] and its value is ['directly given]
|
||||
from the factory `f` (i.e., the value [_is not copied]).
|
||||
* [*Throws:] Whatever the `T` constructor called by the factory throws.
|
||||
* [*Notes:] See [link boost_optional.in_place_factories In-Place Factories]
|
||||
* [*Exception Safety:] Exceptions can only be thrown during the call to
|
||||
the `T` constructor used by the factory; in that case, the `optional` object
|
||||
will be reset to be ['uninitialized].
|
||||
|
||||
__SPACE__
|
||||
|
||||
[#reference_optional_reset_value]
|
||||
|
||||
[: `void optional<T` ['(not a ref)]`>::reset( T const& v ) ;`]
|
||||
@ -641,7 +660,7 @@ __SPACE__
|
||||
[: `optional<T>::operator `['unspecified-bool-type]`() const ;`]
|
||||
|
||||
* [*Returns:] An unspecified value which if used on a boolean context
|
||||
is equivalent to (`get() != 0`)
|
||||
is equivalent to (`get_ptr() != 0`)
|
||||
* [*Throws:] Nothing.
|
||||
* [*Example:]
|
||||
``
|
||||
@ -678,15 +697,7 @@ __SPACE__
|
||||
|
||||
[: `bool optional<T>::is_initialized() const ;`]
|
||||
|
||||
* [*Returns: ] `true` if the `optional` is initialized, `false` otherwise.
|
||||
* [*Throws:] Nothing.
|
||||
* [*Example:]
|
||||
``
|
||||
optional<T> def ;
|
||||
assert ( !def.is_initialized() );
|
||||
optional<T> opt ( v ) ;
|
||||
assert ( opt.is_initialized() );
|
||||
``
|
||||
* [*Deprecated:] Same as `operator `['unspecified-bool-type]`() ;`
|
||||
|
||||
__SPACE__
|
||||
|
||||
|
||||
@ -1,4 +1,4 @@
|
||||
|
||||
|
||||
[section Optional references]
|
||||
|
||||
This library allows the template parameter `T` to be of reference type:
|
||||
@ -37,7 +37,7 @@ the first time) to the object. Clearly, there is no other choice.
|
||||
assert(x==2);
|
||||
|
||||
If you assign to a bare C++ reference, the assignment is forwarded to the
|
||||
referenced object; it's value changes but the reference is never rebound.
|
||||
referenced object; its value changes but the reference is never rebound.
|
||||
|
||||
int a = 1 ;
|
||||
int& ra = a ;
|
||||
@ -95,15 +95,15 @@ use Optional's assignment without explicitly handling the previous
|
||||
initialization state unless your code is capable of functioning whether
|
||||
after the assignment, `a` aliases the same object as `b` or not.
|
||||
|
||||
That is, you would have to discriminate in order to be consistency.
|
||||
That is, you would have to discriminate in order to be consistent.
|
||||
|
||||
If in your code rebinding to another object is not an option, then is very
|
||||
likely that binding for the fist time isn't either. In such case, assignment
|
||||
If in your code rebinding to another object is not an option, then it is very
|
||||
likely that binding for the first time isn't either. In such case, assignment
|
||||
to an ['uninitialized ] `optional<T&>` shall be prohibited. It is quite possible
|
||||
that in such scenario the precondition that the lvalue must be already
|
||||
initialized exist. If it doesn't, then binding for the first time is OK
|
||||
that in such a scenario it is a precondition that the lvalue must be already
|
||||
initialized. If it isn't, then binding for the first time is OK
|
||||
while rebinding is not which is IMO very unlikely.
|
||||
In such scenario, you can assign the value itself directly, as in:
|
||||
In such a scenario, you can assign the value itself directly, as in:
|
||||
|
||||
assert(!!opt);
|
||||
*opt=value;
|
||||
@ -120,7 +120,7 @@ a fully constructed object, often temporary, just to follow the copy from:
|
||||
|
||||
struct X
|
||||
{
|
||||
X ( int, std:::string ) ;
|
||||
X ( int, std::string ) ;
|
||||
} ;
|
||||
|
||||
class W
|
||||
@ -291,7 +291,7 @@ Because of the current implementation (see [link boost_optional.implementation_n
|
||||
* `template<class U> optional<T>::operator= ( optional<U> const& )`
|
||||
* `template<class InPlaceFactory> optional<T>::operator= ( InPlaceFactory const& )`
|
||||
* `template<class TypedInPlaceFactory> optional<T>::operator= ( TypedInPlaceFactory const& ) `
|
||||
* `optional<T>:::reset ( T const&)`
|
||||
* `optional<T>::reset ( T const&)`
|
||||
|
||||
Can only ['guarantee] the [_basic exception safety]: The lvalue optional is
|
||||
left [_uninitialized] if an exception is thrown (any previous value is ['first]
|
||||
|
||||
@ -17,6 +17,7 @@
|
||||
|
||||
#include <new>
|
||||
#include <algorithm>
|
||||
#include <iosfwd>
|
||||
|
||||
#include <boost/config.hpp>
|
||||
#include <boost/assert.hpp>
|
||||
@ -127,7 +128,7 @@ class aligned_storage
|
||||
union
|
||||
// This works around GCC warnings about breaking strict aliasing rules when casting storage address to T*
|
||||
#if defined(BOOST_OPTIONAL_DETAIL_USE_ATTRIBUTE_MAY_ALIAS)
|
||||
__attribute__((may_alias))
|
||||
__attribute__((__may_alias__))
|
||||
#endif
|
||||
dummy_u
|
||||
{
|
||||
@ -476,7 +477,7 @@ class optional_base : public optional_tag
|
||||
#if BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x581))
|
||||
void destroy_impl ( is_not_reference_tag ) { get_ptr_impl()->internal_type::~internal_type() ; m_initialized = false ; }
|
||||
#else
|
||||
void destroy_impl ( is_not_reference_tag ) { get_ptr_impl()->T::~T() ; m_initialized = false ; }
|
||||
void destroy_impl ( is_not_reference_tag ) { get_ptr_impl()->~T() ; m_initialized = false ; }
|
||||
#endif
|
||||
|
||||
void destroy_impl ( is_reference_tag ) { m_initialized = false ; }
|
||||
@ -743,6 +744,11 @@ get_pointer ( optional<T>& opt )
|
||||
return opt.get_ptr() ;
|
||||
}
|
||||
|
||||
// Forward declaration to prevent operator safe-bool from being used.
|
||||
template<class CharType, class CharTrait, class T>
|
||||
std::basic_ostream<CharType, CharTrait>&
|
||||
operator<<(std::basic_ostream<CharType, CharTrait>& out, optional<T> const& v);
|
||||
|
||||
// optional's relational operators ( ==, !=, <, >, <=, >= ) have deep-semantics (compare values).
|
||||
// WARNING: This is UNLIKE pointers. Use equal_pointees()/less_pointess() in generic code instead.
|
||||
|
||||
@ -890,12 +896,12 @@ bool operator >= ( optional<T> const& x, none_t y )
|
||||
|
||||
template<class T>
|
||||
inline
|
||||
bool operator == ( none_t x, optional<T> const& y )
|
||||
bool operator == ( none_t , optional<T> const& y )
|
||||
{ return equal_pointees(optional<T>() ,y); }
|
||||
|
||||
template<class T>
|
||||
inline
|
||||
bool operator < ( none_t x, optional<T> const& y )
|
||||
bool operator < ( none_t , optional<T> const& y )
|
||||
{ return less_pointees(optional<T>() ,y); }
|
||||
|
||||
template<class T>
|
||||
|
||||
@ -840,11 +840,21 @@ void test_with_builtin_types()
|
||||
test_none( ARG(double) ) ;
|
||||
}
|
||||
|
||||
// MSVC < 11.0 doesn't destroy X when we call ptr->VBase::VBase.
|
||||
// Make sure that we work around this bug.
|
||||
struct VBase : virtual X
|
||||
{
|
||||
VBase(int v) : X(v) {}
|
||||
// MSVC 8.0 doesn't generate this correctly...
|
||||
VBase(const VBase& other) : X(static_cast<const X&>(other)) {}
|
||||
};
|
||||
|
||||
void test_with_class_type()
|
||||
{
|
||||
TRACE( std::endl << BOOST_CURRENT_FUNCTION );
|
||||
|
||||
test_basics( ARG(X) );
|
||||
test_basics( ARG(VBase) );
|
||||
test_conditional_ctor_and_get_valur_or( ARG(X) );
|
||||
test_direct_value_manip( ARG(X) );
|
||||
test_uninitialized_access( ARG(X) );
|
||||
|
||||
Reference in New Issue
Block a user