<aname="boost_optional.a_note_about_optional_bool_"></a><aclass="link"href="a_note_about_optional_bool_.html"title="A note about optional<bool>">A note about
<aname="boost_optional.a_note_about_optional_bool_"></a><aclass="link"href="a_note_about_optional_bool_.html"title="A note about optional<bool>">A note about
<aname="boost_optional.dependencies_and_portability"></a><aclass="link"href="dependencies_and_portability.html"title="Dependencies and Portability">Dependencies
<aname="boost_optional.dependencies_and_portability"></a><aclass="link"href="dependencies_and_portability.html"title="Dependencies and Portability">Dependencies
type, in the sequel, those entries whose semantic depends on <codeclass="computeroutput"><spanclass="identifier">T</span></code> being of reference type or not will be
type, in the sequel, those entries whose semantic depends on <codeclass="computeroutput"><spanclass="identifier">T</span></code> being of reference type or not will be
If the entry reads: <codeclass="computeroutput"><spanclass="identifier">optional</span><spanclass="special"><</span><spanclass="identifier">T</span></code><spanclass="emphasis"><em>(not
If the entry reads: <codeclass="computeroutput"><spanclass="identifier">optional</span><spanclass="special"><</span><spanclass="identifier">T</span></code><spanclass="emphasis"><em>(not
a ref)</em></span><codeclass="computeroutput"><spanclass="special">></span></code>, the description
a ref)</em></span><codeclass="computeroutput"><spanclass="special">></span></code>, the description
corresponds only to the case where <codeclass="computeroutput"><spanclass="identifier">T</span></code>
corresponds only to the case where <codeclass="computeroutput"><spanclass="identifier">T</span></code>
is not of reference type.
is not of reference type.
</li>
</li>
<li>
<liclass="listitem">
If the entry reads: <codeclass="computeroutput"><spanclass="identifier">optional</span><spanclass="special"><</span><spanclass="identifier">T</span><spanclass="special">&></span></code>,
If the entry reads: <codeclass="computeroutput"><spanclass="identifier">optional</span><spanclass="special"><</span><spanclass="identifier">T</span><spanclass="special">&></span></code>,
the description corresponds only to the case where <codeclass="computeroutput"><spanclass="identifier">T</span></code>
the description corresponds only to the case where <codeclass="computeroutput"><spanclass="identifier">T</span></code>
is of reference type.
is of reference type.
</li>
</li>
<li>
<liclass="listitem">
If the entry reads: <codeclass="computeroutput"><spanclass="identifier">optional</span><spanclass="special"><</span><spanclass="identifier">T</span><spanclass="special">></span></code>,
If the entry reads: <codeclass="computeroutput"><spanclass="identifier">optional</span><spanclass="special"><</span><spanclass="identifier">T</span><spanclass="special">></span></code>,
<spanclass="bold"><strong>Effect:</strong></span> Default-Constructs an <codeclass="computeroutput"><spanclass="identifier">optional</span></code>.
<spanclass="bold"><strong>Effect:</strong></span> Default-Constructs an <codeclass="computeroutput"><spanclass="identifier">optional</span></code>.
</li>
</li>
<li>
<liclass="listitem">
<spanclass="bold"><strong>Postconditions:</strong></span><codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is <spanclass="underline">uninitialized</span>.
<spanclass="bold"><strong>Postconditions:</strong></span><codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is <spanclass="underline">uninitialized</span>.
<spanclass="bold"><strong>Effect:</strong></span> Constructs an <codeclass="computeroutput"><spanclass="identifier">optional</span></code>
<spanclass="bold"><strong>Effect:</strong></span> Constructs an <codeclass="computeroutput"><spanclass="identifier">optional</span></code>
uninitialized.
uninitialized.
</li>
</li>
<li>
<liclass="listitem">
<spanclass="bold"><strong>Postconditions:</strong></span><codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is <spanclass="underline">uninitialized</span>.
<spanclass="bold"><strong>Postconditions:</strong></span><codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is <spanclass="underline">uninitialized</span>.
The expression <codeclass="computeroutput"><spanclass="identifier">boost</span><spanclass="special">::</span><spanclass="identifier">none</span></code> denotes an instance of <codeclass="computeroutput"><spanclass="identifier">boost</span><spanclass="special">::</span><spanclass="identifier">none_t</span></code> that can be used as the parameter.
The expression <codeclass="computeroutput"><spanclass="identifier">boost</span><spanclass="special">::</span><spanclass="identifier">none</span></code> denotes an instance of <codeclass="computeroutput"><spanclass="identifier">boost</span><spanclass="special">::</span><spanclass="identifier">none_t</span></code> that can be used as the parameter.
<spanclass="bold"><strong>Effect:</strong></span> Directly-Constructs an <codeclass="computeroutput"><spanclass="identifier">optional</span></code>.
<spanclass="bold"><strong>Effect:</strong></span> Directly-Constructs an <codeclass="computeroutput"><spanclass="identifier">optional</span></code>.
</li>
</li>
<li>
<liclass="listitem">
<spanclass="bold"><strong>Postconditions:</strong></span><codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is <spanclass="underline">initialized</span>
<spanclass="bold"><strong>Postconditions:</strong></span><codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is <spanclass="underline">initialized</span>
and its value is a<spanclass="emphasis"><em>copy</em></span> of <codeclass="computeroutput"><spanclass="identifier">v</span></code>.
and its value is a<spanclass="emphasis"><em>copy</em></span> of <codeclass="computeroutput"><spanclass="identifier">v</span></code>.
<spanclass="identifier">T</span><spanclass="keyword">const</span><spanclass="special">&</span><spanclass="special">)</span></code> is
<spanclass="identifier">T</span><spanclass="keyword">const</span><spanclass="special">&</span><spanclass="special">)</span></code> is
called.
called.
</li>
</li>
<li>
<liclass="listitem">
<spanclass="bold"><strong>Exception Safety:</strong></span> Exceptions can only be
<spanclass="bold"><strong>Exception Safety:</strong></span> Exceptions can only be
thrown during <codeclass="computeroutput"><spanclass="identifier">T</span><spanclass="special">::</span><spanclass="identifier">T</span><spanclass="special">(</span><spanclass="identifier">T</span>
thrown during <codeclass="computeroutput"><spanclass="identifier">T</span><spanclass="special">::</span><spanclass="identifier">T</span><spanclass="special">(</span><spanclass="identifier">T</span>
<spanclass="bold"><strong>Effect:</strong></span> Directly-Constructs an <codeclass="computeroutput"><spanclass="identifier">optional</span></code>.
<spanclass="bold"><strong>Effect:</strong></span> Directly-Constructs an <codeclass="computeroutput"><spanclass="identifier">optional</span></code>.
</li>
</li>
<li>
<liclass="listitem">
<spanclass="bold"><strong>Postconditions:</strong></span><codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is <spanclass="underline">initialized</span>
<spanclass="bold"><strong>Postconditions:</strong></span><codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is <spanclass="underline">initialized</span>
and its value is an instance of an internal type wrapping the reference
and its value is an instance of an internal type wrapping the reference
is initialized and its value is a <spanclass="emphasis"><em>copy</em></span> of the value
is initialized and its value is a <spanclass="emphasis"><em>copy</em></span> of the value
of <codeclass="computeroutput"><spanclass="identifier">rhs</span></code>; else <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is uninitialized.
of <codeclass="computeroutput"><spanclass="identifier">rhs</span></code>; else <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is uninitialized.
<spanclass="bold"><strong>Notes:</strong></span> If rhs is initialized, <codeclass="computeroutput"><spanclass="identifier">T</span><spanclass="special">::</span><spanclass="identifier">T</span><spanclass="special">(</span><spanclass="identifier">T</span><spanclass="keyword">const</span><spanclass="special">&</span><spanclass="special">)</span></code> is
<spanclass="bold"><strong>Notes:</strong></span> If rhs is initialized, <codeclass="computeroutput"><spanclass="identifier">T</span><spanclass="special">::</span><spanclass="identifier">T</span><spanclass="special">(</span><spanclass="identifier">T</span><spanclass="keyword">const</span><spanclass="special">&</span><spanclass="special">)</span></code> is
called.
called.
</li>
</li>
<li>
<liclass="listitem">
<spanclass="bold"><strong>Exception Safety:</strong></span> Exceptions can only be
<spanclass="bold"><strong>Exception Safety:</strong></span> Exceptions can only be
thrown during <codeclass="computeroutput"><spanclass="identifier">T</span><spanclass="special">::</span><spanclass="identifier">T</span><spanclass="special">(</span><spanclass="identifier">T</span>
thrown during <codeclass="computeroutput"><spanclass="identifier">T</span><spanclass="special">::</span><spanclass="identifier">T</span><spanclass="special">(</span><spanclass="identifier">T</span>
<spanclass="identifier">U</span><spanclass="keyword">const</span><spanclass="special">&</span><spanclass="special">)</span></code> is
<spanclass="identifier">U</span><spanclass="keyword">const</span><spanclass="special">&</span><spanclass="special">)</span></code> is
called if <codeclass="computeroutput"><spanclass="identifier">rhs</span></code> is initialized,
called if <codeclass="computeroutput"><spanclass="identifier">rhs</span></code> is initialized,
which requires a valid conversion from <codeclass="computeroutput"><spanclass="identifier">U</span></code>
which requires a valid conversion from <codeclass="computeroutput"><spanclass="identifier">U</span></code>
to <codeclass="computeroutput"><spanclass="identifier">T</span></code>.
to <codeclass="computeroutput"><spanclass="identifier">T</span></code>.
</li>
</li>
<li>
<liclass="listitem">
<spanclass="bold"><strong>Exception Safety:</strong></span> Exceptions can only be
<spanclass="bold"><strong>Exception Safety:</strong></span> Exceptions can only be
thrown during <codeclass="computeroutput"><spanclass="identifier">T</span><spanclass="special">::</span><spanclass="identifier">T</span><spanclass="special">(</span><spanclass="identifier">U</span>
thrown during <codeclass="computeroutput"><spanclass="identifier">T</span><spanclass="special">::</span><spanclass="identifier">T</span><spanclass="special">(</span><spanclass="identifier">U</span>
<spanclass="bold"><strong>Effect:</strong></span> Constructs an <codeclass="computeroutput"><spanclass="identifier">optional</span></code>
<spanclass="bold"><strong>Effect:</strong></span> Constructs an <codeclass="computeroutput"><spanclass="identifier">optional</span></code>
with a value of <codeclass="computeroutput"><spanclass="identifier">T</span></code> obtained
with a value of <codeclass="computeroutput"><spanclass="identifier">T</span></code> obtained
from the factory.
from the factory.
</li>
</li>
<li>
<liclass="listitem">
<spanclass="bold"><strong>Postconditions: </strong></span><codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is <spanclass="underline">initialized</span>
<spanclass="bold"><strong>Postconditions: </strong></span><codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is <spanclass="underline">initialized</span>
and its value is <spanclass="emphasis"><em>directly given</em></span> from the factory <codeclass="computeroutput"><spanclass="identifier">f</span></code> (i.e., the value <spanclass="underline">is
and its value is <spanclass="emphasis"><em>directly given</em></span> from the factory <codeclass="computeroutput"><spanclass="identifier">f</span></code> (i.e., the value <spanclass="underline">is
not copied</span>).
not copied</span>).
</li>
</li>
<li>
<liclass="listitem">
<spanclass="bold"><strong>Throws:</strong></span> Whatever the <codeclass="computeroutput"><spanclass="identifier">T</span></code>
<spanclass="bold"><strong>Throws:</strong></span> Whatever the <codeclass="computeroutput"><spanclass="identifier">T</span></code>
constructor called by the factory throws.
constructor called by the factory throws.
</li>
</li>
<li>
<liclass="listitem">
<spanclass="bold"><strong>Notes:</strong></span> See <aclass="link"href="in_place_factories.html"title="In-Place Factories">In-Place
<spanclass="bold"><strong>Notes:</strong></span> See <aclass="link"href="in_place_factories.html"title="In-Place Factories">In-Place
Factories</a>
Factories</a>
</li>
</li>
<li>
<liclass="listitem">
<spanclass="bold"><strong>Exception Safety:</strong></span> Exceptions can only be
<spanclass="bold"><strong>Exception Safety:</strong></span> Exceptions can only be
thrown during the call to the <codeclass="computeroutput"><spanclass="identifier">T</span></code>
thrown during the call to the <codeclass="computeroutput"><spanclass="identifier">T</span></code>
constructor used by the factory; in that case, this constructor has no effect.
constructor used by the factory; in that case, this constructor has no effect.
<spanclass="bold"><strong>Effect:</strong></span> Assigns the value <codeclass="computeroutput"><spanclass="identifier">rhs</span></code> to an <codeclass="computeroutput"><spanclass="identifier">optional</span></code>.
<spanclass="bold"><strong>Effect:</strong></span> Assigns the value <codeclass="computeroutput"><spanclass="identifier">rhs</span></code> to an <codeclass="computeroutput"><spanclass="identifier">optional</span></code>.
</li>
</li>
<li>
<liclass="listitem">
<spanclass="bold"><strong>Postconditions: </strong></span><codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is initialized and its value is a <spanclass="emphasis"><em>copy</em></span>
<spanclass="bold"><strong>Postconditions: </strong></span><codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is initialized and its value is a <spanclass="emphasis"><em>copy</em></span>
of <codeclass="computeroutput"><spanclass="identifier">rhs</span></code>.
of <codeclass="computeroutput"><spanclass="identifier">rhs</span></code>.
</li>
</li>
<li>
<liclass="listitem">
<spanclass="bold"><strong>Throws:</strong></span> Whatever <codeclass="computeroutput"><spanclass="identifier">T</span><spanclass="special">::</span><spanclass="keyword">operator</span><spanclass="special">=(</span><spanclass="identifier">T</span><spanclass="keyword">const</span><spanclass="special">&</span><spanclass="special">)</span></code> or
<spanclass="bold"><strong>Throws:</strong></span> Whatever <codeclass="computeroutput"><spanclass="identifier">T</span><spanclass="special">::</span><spanclass="keyword">operator</span><spanclass="special">=(</span><spanclass="identifier">T</span><spanclass="keyword">const</span><spanclass="special">&</span><spanclass="special">)</span></code> or
<spanclass="bold"><strong>Notes:</strong></span> If <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> was initialized, <codeclass="computeroutput"><spanclass="identifier">T</span></code>'s
<spanclass="bold"><strong>Notes:</strong></span> If <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> was initialized, <codeclass="computeroutput"><spanclass="identifier">T</span></code>'s
assignment operator is used, otherwise, its copy-constructor is used.
assignment operator is used, otherwise, its copy-constructor is used.
</li>
</li>
<li>
<liclass="listitem">
<spanclass="bold"><strong>Exception Safety:</strong></span> In the event of an exception,
<spanclass="bold"><strong>Exception Safety:</strong></span> In the event of an exception,
the initialization state of <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is unchanged and its value unspecified
the initialization state of <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is unchanged and its value unspecified
as far as <codeclass="computeroutput"><spanclass="identifier">optional</span></code> is concerned
as far as <codeclass="computeroutput"><spanclass="identifier">optional</span></code> is concerned
@ -565,7 +565,7 @@
is initially uninitialized and <codeclass="computeroutput"><spanclass="identifier">T</span></code>'s
is initially uninitialized and <codeclass="computeroutput"><spanclass="identifier">T</span></code>'s
<spanclass="emphasis"><em>copy constructor</em></span> fails, <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is left properly uninitialized.
<spanclass="emphasis"><em>copy constructor</em></span> fails, <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is left properly uninitialized.
<spanclass="bold"><strong>Effect:</strong></span> (Re)binds thee wrapped reference.
<spanclass="bold"><strong>Effect:</strong></span> (Re)binds thee wrapped reference.
</li>
</li>
<li>
<liclass="listitem">
<spanclass="bold"><strong>Postconditions: </strong></span><codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is initialized and it references the
<spanclass="bold"><strong>Postconditions: </strong></span><codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is initialized and it references the
same object referenced by <codeclass="computeroutput"><spanclass="identifier">rhs</span></code>.
same object referenced by <codeclass="computeroutput"><spanclass="identifier">rhs</span></code>.
</li>
</li>
<li>
<liclass="listitem">
<spanclass="bold"><strong>Notes:</strong></span> If <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> was initialized, is is <spanclass="emphasis"><em>rebound</em></span>
<spanclass="bold"><strong>Notes:</strong></span> If <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> was initialized, is is <spanclass="emphasis"><em>rebound</em></span>
to the new object. See <aclass="link"href="rebinding_semantics_for_assignment_of_optional_references.html"title="Rebinding semantics for assignment of optional references">here</a>
to the new object. See <aclass="link"href="rebinding_semantics_for_assignment_of_optional_references.html"title="Rebinding semantics for assignment of optional references">here</a>
<spanclass="bold"><strong>Effect:</strong></span> Assigns another <codeclass="computeroutput"><spanclass="identifier">optional</span></code>
<spanclass="bold"><strong>Effect:</strong></span> Assigns another <codeclass="computeroutput"><spanclass="identifier">optional</span></code>
to an <codeclass="computeroutput"><spanclass="identifier">optional</span></code>.
to an <codeclass="computeroutput"><spanclass="identifier">optional</span></code>.
</li>
</li>
<li>
<liclass="listitem">
<spanclass="bold"><strong>Postconditions:</strong></span> If <codeclass="computeroutput"><spanclass="identifier">rhs</span></code>
<spanclass="bold"><strong>Postconditions:</strong></span> If <codeclass="computeroutput"><spanclass="identifier">rhs</span></code>
is initialized, <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code>
is initialized, <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code>
is initialized and its value is a <spanclass="emphasis"><em>copy</em></span> of the value
is initialized and its value is a <spanclass="emphasis"><em>copy</em></span> of the value
of <codeclass="computeroutput"><spanclass="identifier">rhs</span></code>; else <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is uninitialized.
of <codeclass="computeroutput"><spanclass="identifier">rhs</span></code>; else <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is uninitialized.
</li>
</li>
<li>
<liclass="listitem">
<spanclass="bold"><strong>Throws:</strong></span> Whatever <codeclass="computeroutput"><spanclass="identifier">T</span><spanclass="special">::</span><spanclass="keyword">operator</span><spanclass="special">(</span><spanclass="identifier">T</span><spanclass="keyword">const</span><spanclass="special">&)</span></code> or <codeclass="computeroutput"><spanclass="identifier">T</span><spanclass="special">::</span><spanclass="identifier">T</span><spanclass="special">(</span>
<spanclass="bold"><strong>Throws:</strong></span> Whatever <codeclass="computeroutput"><spanclass="identifier">T</span><spanclass="special">::</span><spanclass="keyword">operator</span><spanclass="special">(</span><spanclass="identifier">T</span><spanclass="keyword">const</span><spanclass="special">&)</span></code> or <codeclass="computeroutput"><spanclass="identifier">T</span><spanclass="special">::</span><spanclass="identifier">T</span><spanclass="special">(</span>
<spanclass="bold"><strong>Notes:</strong></span> If both <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> and <codeclass="computeroutput"><spanclass="identifier">rhs</span></code>
<spanclass="bold"><strong>Notes:</strong></span> If both <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> and <codeclass="computeroutput"><spanclass="identifier">rhs</span></code>
are initially initialized, <codeclass="computeroutput"><spanclass="identifier">T</span></code>'s
are initially initialized, <codeclass="computeroutput"><spanclass="identifier">T</span></code>'s
<spanclass="emphasis"><em>assignment operator</em></span> is used. If <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is initially initialized but <codeclass="computeroutput"><spanclass="identifier">rhs</span></code> is uninitialized, <codeclass="computeroutput"><spanclass="identifier">T</span></code>'s
<spanclass="emphasis"><em>assignment operator</em></span> is used. If <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is initially initialized but <codeclass="computeroutput"><spanclass="identifier">rhs</span></code> is uninitialized, <codeclass="computeroutput"><spanclass="identifier">T</span></code>'s
[destructor] is called. If <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is initially uninitialized but <codeclass="computeroutput"><spanclass="identifier">rhs</span></code> is initialized, <codeclass="computeroutput"><spanclass="identifier">T</span></code>'s
[destructor] is called. If <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is initially uninitialized but <codeclass="computeroutput"><spanclass="identifier">rhs</span></code> is initialized, <codeclass="computeroutput"><spanclass="identifier">T</span></code>'s
<spanclass="emphasis"><em>copy constructor</em></span> is called.
<spanclass="emphasis"><em>copy constructor</em></span> is called.
</li>
</li>
<li>
<liclass="listitem">
<spanclass="bold"><strong>Exception Safety:</strong></span> In the event of an exception,
<spanclass="bold"><strong>Exception Safety:</strong></span> In the event of an exception,
the initialization state of <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is unchanged and its value unspecified
the initialization state of <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is unchanged and its value unspecified
as far as optional is concerned (it is up to <codeclass="computeroutput"><spanclass="identifier">T</span></code>'s
as far as optional is concerned (it is up to <codeclass="computeroutput"><spanclass="identifier">T</span></code>'s
@ -676,7 +676,7 @@
is initially uninitialized and <codeclass="computeroutput"><spanclass="identifier">T</span></code>'s
is initially uninitialized and <codeclass="computeroutput"><spanclass="identifier">T</span></code>'s
<spanclass="emphasis"><em>copy constructor</em></span> fails, <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is left properly uninitialized.
<spanclass="emphasis"><em>copy constructor</em></span> fails, <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is left properly uninitialized.
<spanclass="bold"><strong>Effect:</strong></span> (Re)binds thee wrapped reference.
<spanclass="bold"><strong>Effect:</strong></span> (Re)binds thee wrapped reference.
</li>
</li>
<li>
<liclass="listitem">
<spanclass="bold"><strong>Postconditions:</strong></span> If <codeclass="computeroutput"><spanclass="special">*</span><spanclass="identifier">rhs</span></code> is initialized, <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is initialized and it references the
<spanclass="bold"><strong>Postconditions:</strong></span> If <codeclass="computeroutput"><spanclass="special">*</span><spanclass="identifier">rhs</span></code> is initialized, <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is initialized and it references the
same object referenced by <codeclass="computeroutput"><spanclass="special">*</span><spanclass="identifier">rhs</span></code>; otherwise, <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is uninitialized (and references no object).
same object referenced by <codeclass="computeroutput"><spanclass="special">*</span><spanclass="identifier">rhs</span></code>; otherwise, <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is uninitialized (and references no object).
</li>
</li>
<li>
<liclass="listitem">
<spanclass="bold"><strong>Notes:</strong></span> If <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> was initialized and so is *rhs, this
<spanclass="bold"><strong>Notes:</strong></span> If <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> was initialized and so is *rhs, this
is is <spanclass="emphasis"><em>rebound</em></span> to the new object. See <aclass="link"href="rebinding_semantics_for_assignment_of_optional_references.html"title="Rebinding semantics for assignment of optional references">here</a>
is is <spanclass="emphasis"><em>rebound</em></span> to the new object. See <aclass="link"href="rebinding_semantics_for_assignment_of_optional_references.html"title="Rebinding semantics for assignment of optional references">here</a>
<spanclass="bold"><strong>Effect:</strong></span> Assigns another convertible optional
<spanclass="bold"><strong>Effect:</strong></span> Assigns another convertible optional
to an optional.
to an optional.
</li>
</li>
<li>
<liclass="listitem">
<spanclass="bold"><strong>Postconditions:</strong></span> If <codeclass="computeroutput"><spanclass="identifier">rhs</span></code>
<spanclass="bold"><strong>Postconditions:</strong></span> If <codeclass="computeroutput"><spanclass="identifier">rhs</span></code>
is initialized, <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code>
is initialized, <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code>
is initialized and its value is a <spanclass="emphasis"><em>copy</em></span> of the value
is initialized and its value is a <spanclass="emphasis"><em>copy</em></span> of the value
of <codeclass="computeroutput"><spanclass="identifier">rhs</span></code><spanclass="emphasis"><em>converted</em></span>
of <codeclass="computeroutput"><spanclass="identifier">rhs</span></code><spanclass="emphasis"><em>converted</em></span>
to type <codeclass="computeroutput"><spanclass="identifier">T</span></code>; else <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is uninitialized.
to type <codeclass="computeroutput"><spanclass="identifier">T</span></code>; else <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is uninitialized.
</li>
</li>
<li>
<liclass="listitem">
<spanclass="bold"><strong>Throws:</strong></span> Whatever <codeclass="computeroutput"><spanclass="identifier">T</span><spanclass="special">::</span><spanclass="keyword">operator</span><spanclass="special">=(</span><spanclass="identifier">U</span><spanclass="keyword">const</span><spanclass="special">&</span><spanclass="special">)</span></code> or
<spanclass="bold"><strong>Throws:</strong></span> Whatever <codeclass="computeroutput"><spanclass="identifier">T</span><spanclass="special">::</span><spanclass="keyword">operator</span><spanclass="special">=(</span><spanclass="identifier">U</span><spanclass="keyword">const</span><spanclass="special">&</span><spanclass="special">)</span></code> or
<spanclass="bold"><strong>Notes:</strong></span> If both <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> and rhs are initially initialized, <codeclass="computeroutput"><spanclass="identifier">T</span></code>'s <spanclass="emphasis"><em>assignment operator</em></span>
<spanclass="bold"><strong>Notes:</strong></span> If both <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> and rhs are initially initialized, <codeclass="computeroutput"><spanclass="identifier">T</span></code>'s <spanclass="emphasis"><em>assignment operator</em></span>
(from <codeclass="computeroutput"><spanclass="identifier">U</span></code>) is used. If <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is initially
(from <codeclass="computeroutput"><spanclass="identifier">U</span></code>) is used. If <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is initially
initialized but <codeclass="computeroutput"><spanclass="identifier">rhs</span></code> is uninitialized,
initialized but <codeclass="computeroutput"><spanclass="identifier">rhs</span></code> is uninitialized,
<spanclass="bold"><strong>Exception Safety:</strong></span> In the event of an exception,
<spanclass="bold"><strong>Exception Safety:</strong></span> In the event of an exception,
the initialization state of <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is unchanged and its value unspecified
the initialization state of <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is unchanged and its value unspecified
as far as optional is concerned (it is up to <codeclass="computeroutput"><spanclass="identifier">T</span></code>'s
as far as optional is concerned (it is up to <codeclass="computeroutput"><spanclass="identifier">T</span></code>'s
@ -787,7 +787,7 @@
is initially uninitialized and <codeclass="computeroutput"><spanclass="identifier">T</span></code>'s
is initially uninitialized and <codeclass="computeroutput"><spanclass="identifier">T</span></code>'s
converting constructor fails, <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is left properly uninitialized.
converting constructor fails, <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is left properly uninitialized.
<spanclass="bold"><strong>Deprecated:</strong></span> same as <codeclass="computeroutput"><spanclass="keyword">operator</span><spanclass="special">=</span><spanclass="special">(</span><spanclass="identifier">T</span>
<spanclass="bold"><strong>Deprecated:</strong></span> same as <codeclass="computeroutput"><spanclass="keyword">operator</span><spanclass="special">=</span><spanclass="special">(</span><spanclass="identifier">T</span>
<spanclass="bold"><strong>Deprecated:</strong></span> Same as <codeclass="computeroutput"><spanclass="keyword">operator</span><spanclass="special">=(</span><spanclass="identifier">detail</span><spanclass="special">::</span><spanclass="identifier">none_t</span><spanclass="special">);</span></code>
<spanclass="bold"><strong>Deprecated:</strong></span> Same as <codeclass="computeroutput"><spanclass="keyword">operator</span><spanclass="special">=(</span><spanclass="identifier">detail</span><spanclass="special">::</span><spanclass="identifier">none_t</span><spanclass="special">);</span></code>
<spanclass="bold"><strong>Requirements:</strong></span><codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is initialized
<spanclass="bold"><strong>Requirements:</strong></span><codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is initialized
</li>
</li>
<li>
<liclass="listitem">
<spanclass="bold"><strong>Returns:</strong></span> A reference to the contained value
<spanclass="bold"><strong>Returns:</strong></span> A reference to the contained value
<spanclass="bold"><strong>Requirements: </strong></span><codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is initialized
<spanclass="bold"><strong>Requirements: </strong></span><codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is initialized
<spanclass="bold"><strong>Returns:</strong></span> If <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is initialized, a pointer to the contained
<spanclass="bold"><strong>Returns:</strong></span> If <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is initialized, a pointer to the contained
<spanclass="bold"><strong>Requirements: </strong></span><codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is initialized.
<spanclass="bold"><strong>Requirements: </strong></span><codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is initialized.
</li>
</li>
<li>
<liclass="listitem">
<spanclass="bold"><strong>Returns:</strong></span> A pointer to the contained value.
<spanclass="bold"><strong>Returns:</strong></span> A pointer to the contained value.
<spanclass="bold"><strong>Returns:</strong></span> An unspecified value which if used
<spanclass="bold"><strong>Returns:</strong></span> An unspecified value which if used
on a boolean context is equivalent to (<codeclass="computeroutput"><spanclass="identifier">get</span><spanclass="special">()</span><spanclass="special">!=</span><spanclass="number">0</span></code>)
on a boolean context is equivalent to (<codeclass="computeroutput"><spanclass="identifier">get</span><spanclass="special">()</span><spanclass="special">!=</span><spanclass="number">0</span></code>)
<spanclass="bold"><strong>Returns:</strong></span> If <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is uninitialized, <codeclass="computeroutput"><spanclass="keyword">true</span></code>;
<spanclass="bold"><strong>Returns:</strong></span> If <codeclass="computeroutput"><spanclass="special">*</span><spanclass="keyword">this</span></code> is uninitialized, <codeclass="computeroutput"><spanclass="keyword">true</span></code>;
<spanclass="bold"><strong>Returns: </strong></span><codeclass="computeroutput"><spanclass="identifier">optional</span><spanclass="special"><</span><spanclass="identifier">T</span><spanclass="special">>(</span><spanclass="identifier">v</span><spanclass="special">)</span></code> for
<spanclass="bold"><strong>Returns: </strong></span><codeclass="computeroutput"><spanclass="identifier">optional</span><spanclass="special"><</span><spanclass="identifier">T</span><spanclass="special">>(</span><spanclass="identifier">v</span><spanclass="special">)</span></code> for
the <spanclass="emphasis"><em>deduced</em></span> type <codeclass="computeroutput"><spanclass="identifier">T</span></code>
the <spanclass="emphasis"><em>deduced</em></span> type <codeclass="computeroutput"><spanclass="identifier">T</span></code>
of <codeclass="computeroutput"><spanclass="identifier">v</span></code>.
of <codeclass="computeroutput"><spanclass="identifier">v</span></code>.
<spanclass="identifier">foo</span><spanclass="special">(</span><spanclass="identifier">make_optional</span><spanclass="special">(</span><spanclass="number">1</span><spanclass="special">+</span><spanclass="number">1</span><spanclass="special">)</span><spanclass="special">)</span><spanclass="special">;</span><spanclass="comment">// Creates an optional<int>
<spanclass="identifier">foo</span><spanclass="special">(</span><spanclass="identifier">make_optional</span><spanclass="special">(</span><spanclass="number">1</span><spanclass="special">+</span><spanclass="number">1</span><spanclass="special">)</span><spanclass="special">)</span><spanclass="special">;</span><spanclass="comment">// Creates an optional<int>
<spanclass="bold"><strong>Returns: </strong></span><codeclass="computeroutput"><spanclass="identifier">optional</span><spanclass="special"><</span><spanclass="identifier">T</span><spanclass="special">>(</span><spanclass="identifier">condition</span><spanclass="special">,</span><spanclass="identifier">v</span><spanclass="special">)</span></code> for
<spanclass="bold"><strong>Returns: </strong></span><codeclass="computeroutput"><spanclass="identifier">optional</span><spanclass="special"><</span><spanclass="identifier">T</span><spanclass="special">>(</span><spanclass="identifier">condition</span><spanclass="special">,</span><spanclass="identifier">v</span><spanclass="special">)</span></code> for
the <spanclass="emphasis"><em>deduced</em></span> type <codeclass="computeroutput"><spanclass="identifier">T</span></code>
the <spanclass="emphasis"><em>deduced</em></span> type <codeclass="computeroutput"><spanclass="identifier">T</span></code>
of <codeclass="computeroutput"><spanclass="identifier">v</span></code>.
of <codeclass="computeroutput"><spanclass="identifier">v</span></code>.
<spanclass="bold"><strong>Returns:</strong></span> If both <codeclass="computeroutput"><spanclass="identifier">x</span></code>
<spanclass="bold"><strong>Returns:</strong></span> If both <codeclass="computeroutput"><spanclass="identifier">x</span></code>
and <codeclass="computeroutput"><spanclass="identifier">y</span></code> are initialized, <codeclass="computeroutput"><spanclass="special">(*</span><spanclass="identifier">x</span><spanclass="special">==</span>
and <codeclass="computeroutput"><spanclass="identifier">y</span></code> are initialized, <codeclass="computeroutput"><spanclass="special">(*</span><spanclass="identifier">x</span><spanclass="special">==</span>
<spanclass="special">*</span><spanclass="identifier">y</span><spanclass="special">)</span></code>. If only <codeclass="computeroutput"><spanclass="identifier">x</span></code>
<spanclass="special">*</span><spanclass="identifier">y</span><spanclass="special">)</span></code>. If only <codeclass="computeroutput"><spanclass="identifier">x</span></code>
or <codeclass="computeroutput"><spanclass="identifier">y</span></code> is initialized, <codeclass="computeroutput"><spanclass="keyword">false</span></code>. If both are uninitialized, <codeclass="computeroutput"><spanclass="keyword">true</span></code>.
or <codeclass="computeroutput"><spanclass="identifier">y</span></code> is initialized, <codeclass="computeroutput"><spanclass="keyword">false</span></code>. If both are uninitialized, <codeclass="computeroutput"><spanclass="keyword">true</span></code>.
<spanclass="bold"><strong>Notes:</strong></span> Pointers have shallow relational
<spanclass="bold"><strong>Notes:</strong></span> Pointers have shallow relational
operators while <codeclass="computeroutput"><spanclass="identifier">optional</span></code>
operators while <codeclass="computeroutput"><spanclass="identifier">optional</span></code>
has deep relational operators. Do not use <codeclass="computeroutput"><spanclass="keyword">operator</span>
has deep relational operators. Do not use <codeclass="computeroutput"><spanclass="keyword">operator</span>
@ -1417,7 +1417,7 @@
or a pointer; use <ahref="../../../../utility/OptionalPointee.html#equal"target="_top"><codeclass="computeroutput"><spanclass="identifier">equal_pointees</span><spanclass="special">()</span></code></a>
or a pointer; use <ahref="../../../../utility/OptionalPointee.html#equal"target="_top"><codeclass="computeroutput"><spanclass="identifier">equal_pointees</span><spanclass="special">()</span></code></a>
<spanclass="bold"><strong>Returns:</strong></span> If <codeclass="computeroutput"><spanclass="identifier">y</span></code>
<spanclass="bold"><strong>Returns:</strong></span> If <codeclass="computeroutput"><spanclass="identifier">y</span></code>
is not initialized, <codeclass="computeroutput"><spanclass="keyword">false</span></code>. If
is not initialized, <codeclass="computeroutput"><spanclass="keyword">false</span></code>. If
<codeclass="computeroutput"><spanclass="identifier">y</span></code> is initialized and <codeclass="computeroutput"><spanclass="identifier">x</span></code> is not initialized, <codeclass="computeroutput"><spanclass="keyword">true</span></code>.
<codeclass="computeroutput"><spanclass="identifier">y</span></code> is initialized and <codeclass="computeroutput"><spanclass="identifier">x</span></code> is not initialized, <codeclass="computeroutput"><spanclass="keyword">true</span></code>.
If both <codeclass="computeroutput"><spanclass="identifier">x</span></code> and <codeclass="computeroutput"><spanclass="identifier">y</span></code> are initialized, <codeclass="computeroutput"><spanclass="special">(*</span><spanclass="identifier">x</span><spanclass="special"><</span><spanclass="special">*</span><spanclass="identifier">y</span><spanclass="special">)</span></code>.
If both <codeclass="computeroutput"><spanclass="identifier">x</span></code> and <codeclass="computeroutput"><spanclass="identifier">y</span></code> are initialized, <codeclass="computeroutput"><spanclass="special">(*</span><spanclass="identifier">x</span><spanclass="special"><</span><spanclass="special">*</span><spanclass="identifier">y</span><spanclass="special">)</span></code>.
<spanclass="bold"><strong>Notes:</strong></span> Pointers have shallow relational
<spanclass="bold"><strong>Notes:</strong></span> Pointers have shallow relational
operators while <codeclass="computeroutput"><spanclass="identifier">optional</span></code>
operators while <codeclass="computeroutput"><spanclass="identifier">optional</span></code>
has deep relational operators. Do not use <codeclass="computeroutput"><spanclass="keyword">operator</span>
has deep relational operators. Do not use <codeclass="computeroutput"><spanclass="keyword">operator</span>
@ -1478,7 +1478,7 @@
or a pointer; use <ahref="../../../../utility/OptionalPointee.html#less"target="_top"><codeclass="computeroutput"><spanclass="identifier">less_pointees</span><spanclass="special">()</span></code></a>
or a pointer; use <ahref="../../../../utility/OptionalPointee.html#less"target="_top"><codeclass="computeroutput"><spanclass="identifier">less_pointees</span><spanclass="special">()</span></code></a>
<spanclass="bold"><strong>Effect:</strong></span> If both <codeclass="computeroutput"><spanclass="identifier">x</span></code>
<spanclass="bold"><strong>Effect:</strong></span> If both <codeclass="computeroutput"><spanclass="identifier">x</span></code>
and <codeclass="computeroutput"><spanclass="identifier">y</span></code> are initialized, calls
and <codeclass="computeroutput"><spanclass="identifier">y</span></code> are initialized, calls
<codeclass="computeroutput"><spanclass="identifier">swap</span><spanclass="special">(*</span><spanclass="identifier">x</span><spanclass="special">,*</span><spanclass="identifier">y</span><spanclass="special">)</span></code> using <codeclass="computeroutput"><spanclass="identifier">std</span><spanclass="special">::</span><spanclass="identifier">swap</span></code>.
<codeclass="computeroutput"><spanclass="identifier">swap</span><spanclass="special">(*</span><spanclass="identifier">x</span><spanclass="special">,*</span><spanclass="identifier">y</span><spanclass="special">)</span></code> using <codeclass="computeroutput"><spanclass="identifier">std</span><spanclass="special">::</span><spanclass="identifier">swap</span></code>.
If only one is initialized, say <codeclass="computeroutput"><spanclass="identifier">x</span></code>,
If only one is initialized, say <codeclass="computeroutput"><spanclass="identifier">x</span></code>,
calls: <codeclass="computeroutput"><spanclass="identifier">y</span><spanclass="special">.</span><spanclass="identifier">reset</span><spanclass="special">(*</span><spanclass="identifier">x</span><spanclass="special">);</span><spanclass="identifier">x</span><spanclass="special">.</span><spanclass="identifier">reset</span><spanclass="special">();</span></code> If none is initialized, does nothing.
calls: <codeclass="computeroutput"><spanclass="identifier">y</span><spanclass="special">.</span><spanclass="identifier">reset</span><spanclass="special">(*</span><spanclass="identifier">x</span><spanclass="special">);</span><spanclass="identifier">x</span><spanclass="special">.</span><spanclass="identifier">reset</span><spanclass="special">();</span></code> If none is initialized, does nothing.
</li>
</li>
<li>
<liclass="listitem">
<spanclass="bold"><strong>Postconditions:</strong></span> The states of <codeclass="computeroutput"><spanclass="identifier">x</span></code> and <codeclass="computeroutput"><spanclass="identifier">y</span></code>
<spanclass="bold"><strong>Postconditions:</strong></span> The states of <codeclass="computeroutput"><spanclass="identifier">x</span></code> and <codeclass="computeroutput"><spanclass="identifier">y</span></code>
interchanged.
interchanged.
</li>
</li>
<li>
<liclass="listitem">
<spanclass="bold"><strong>Throws:</strong></span> If both are initialized, whatever
<spanclass="bold"><strong>Throws:</strong></span> If both are initialized, whatever
throws. If only one is initialized, whatever <codeclass="computeroutput"><spanclass="identifier">T</span><spanclass="special">::</span><spanclass="identifier">T</span><spanclass="special">(</span>
throws. If only one is initialized, whatever <codeclass="computeroutput"><spanclass="identifier">T</span><spanclass="special">::</span><spanclass="identifier">T</span><spanclass="special">(</span>
<spanclass="bold"><strong>Notes:</strong></span> If both are initialized, <codeclass="computeroutput"><spanclass="identifier">swap</span><spanclass="special">(</span><spanclass="identifier">T</span><spanclass="special">&,</span><spanclass="identifier">T</span><spanclass="special">&)</span></code> is used unqualified but with <codeclass="computeroutput"><spanclass="identifier">std</span><spanclass="special">::</span><spanclass="identifier">swap</span></code>
<spanclass="bold"><strong>Notes:</strong></span> If both are initialized, <codeclass="computeroutput"><spanclass="identifier">swap</span><spanclass="special">(</span><spanclass="identifier">T</span><spanclass="special">&,</span><spanclass="identifier">T</span><spanclass="special">&)</span></code> is used unqualified but with <codeclass="computeroutput"><spanclass="identifier">std</span><spanclass="special">::</span><spanclass="identifier">swap</span></code>
introduced in scope. If only one is initialized, <codeclass="computeroutput"><spanclass="identifier">T</span><spanclass="special">::~</span><spanclass="identifier">T</span><spanclass="special">()</span></code>
introduced in scope. If only one is initialized, <codeclass="computeroutput"><spanclass="identifier">T</span><spanclass="special">::~</span><spanclass="identifier">T</span><spanclass="special">()</span></code>
and <codeclass="computeroutput"><spanclass="identifier">T</span><spanclass="special">::</span><spanclass="identifier">T</span><spanclass="special">(</span><spanclass="identifier">T</span>
and <codeclass="computeroutput"><spanclass="identifier">T</span><spanclass="special">::</span><spanclass="identifier">T</span><spanclass="special">(</span><spanclass="identifier">T</span>
<spanclass="bold"><strong>Exception Safety:</strong></span> If both are initialized,
<spanclass="bold"><strong>Exception Safety:</strong></span> If both are initialized,
this operation has the exception safety guarantees of <codeclass="computeroutput"><spanclass="identifier">swap</span><spanclass="special">(</span><spanclass="identifier">T</span><spanclass="special">&,</span><spanclass="identifier">T</span><spanclass="special">&)</span></code>.
this operation has the exception safety guarantees of <codeclass="computeroutput"><spanclass="identifier">swap</span><spanclass="special">(</span><spanclass="identifier">T</span><spanclass="special">&,</span><spanclass="identifier">T</span><spanclass="special">&)</span></code>.
If only one is initialized, it has the same basic guarantee as <codeclass="computeroutput"><spanclass="identifier">optional</span><spanclass="special"><</span><spanclass="identifier">T</span><spanclass="special">>::</span><spanclass="identifier">reset</span><spanclass="special">(</span><spanclass="identifier">T</span><spanclass="keyword">const</span><spanclass="special">&</span><spanclass="special">)</span></code>.
If only one is initialized, it has the same basic guarantee as <codeclass="computeroutput"><spanclass="identifier">optional</span><spanclass="special"><</span><spanclass="identifier">T</span><spanclass="special">>::</span><spanclass="identifier">reset</span><spanclass="special">(</span><spanclass="identifier">T</span><spanclass="keyword">const</span><spanclass="special">&</span><spanclass="special">)</span></code>.
between containers compare container size and if match, contained value
between containers compare container size and if match, contained value
</li>
</li>
<li>
<liclass="listitem">
If the container is not empty (contains an object of type <codeclass="computeroutput"><spanclass="identifier">T</span></code>), it is modeling an <spanclass="emphasis"><em>initialized</em></span>
If the container is not empty (contains an object of type <codeclass="computeroutput"><spanclass="identifier">T</span></code>), it is modeling an <spanclass="emphasis"><em>initialized</em></span>
optional.
optional.
</li>
</li>
<li>
<liclass="listitem">
If the container is empty, it is modeling an <spanclass="emphasis"><em>uninitialized</em></span>
If the container is empty, it is modeling an <spanclass="emphasis"><em>uninitialized</em></span>
optional.
optional.
</li>
</li>
<li>
<liclass="listitem">
Testing if the container is empty models testing if the optional is initialized
Testing if the container is empty models testing if the optional is initialized
</li>
</li>
<li>
<liclass="listitem">
Trying to extract a <codeclass="computeroutput"><spanclass="identifier">T</span></code> from
Trying to extract a <codeclass="computeroutput"><spanclass="identifier">T</span></code> from
an empty container models the undefined behavior of trying to access the
an empty container models the undefined behavior of trying to access the
We can draw from the purpose of <codeclass="computeroutput"><spanclass="identifier">optional</span><spanclass="special"><</span><spanclass="identifier">T</span><spanclass="special">></span></code>
We can draw from the purpose of <codeclass="computeroutput"><spanclass="identifier">optional</span><spanclass="special"><</span><spanclass="identifier">T</span><spanclass="special">></span></code>
<divclass="section"title="Optional local variables">
<divclass="titlepage"><div><div><h3class="title">
<divclass="titlepage"><div><div><h3class="title">
<aname="boost_optional.examples.optional_local_variables"></a><aclass="link"href="examples.html#boost_optional.examples.optional_local_variables"title="Optional local variables">Optional
<aname="boost_optional.examples.optional_local_variables"></a><aclass="link"href="examples.html#boost_optional.examples.optional_local_variables"title="Optional local variables">Optional
local variables</a>
local variables</a>
@ -78,7 +78,7 @@
<spanclass="keyword">else</span><spanclass="identifier">print</span><spanclass="special">(</span><spanclass="string">"employer's name not found!"</span><spanclass="special">);</span>
<spanclass="keyword">else</span><spanclass="identifier">print</span><spanclass="special">(</span><spanclass="string">"employer's name not found!"</span><spanclass="special">);</span>
</pre>
</pre>
</div>
</div>
<divclass="section"lang="en">
<divclass="section"title="Optional data members">
<divclass="titlepage"><div><div><h3class="title">
<divclass="titlepage"><div><div><h3class="title">
<aname="boost_optional.examples.optional_data_members"></a><aclass="link"href="examples.html#boost_optional.examples.optional_data_members"title="Optional data members">Optional
<aname="boost_optional.examples.optional_data_members"></a><aclass="link"href="examples.html#boost_optional.examples.optional_data_members"title="Optional data members">Optional
Provide the no-throw guarantee (assuming a no-throw <codeclass="computeroutput"><spanclass="identifier">T</span><spanclass="special">::~</span><spanclass="identifier">T</span><spanclass="special">()</span></code>)
Provide the no-throw guarantee (assuming a no-throw <codeclass="computeroutput"><spanclass="identifier">T</span><spanclass="special">::~</span><spanclass="identifier">T</span><spanclass="special">()</span></code>)
<spanclass="underline">TypedInPlaceFactories</span>: those which
<spanclass="underline">TypedInPlaceFactories</span>: those which
take the target type as a primary template parameter.
take the target type as a primary template parameter.
</li>
</li>
<li>
<liclass="listitem">
<spanclass="underline">InPlaceFactories</span>: those with a template
<spanclass="underline">InPlaceFactories</span>: those with a template
<codeclass="computeroutput"><spanclass="identifier">construct</span><spanclass="special">(</span><spanclass="keyword">void</span><spanclass="special">*)</span></code> member
<codeclass="computeroutput"><spanclass="identifier">construct</span><spanclass="special">(</span><spanclass="keyword">void</span><spanclass="special">*)</span></code> member
Copies of <codeclass="computeroutput"><spanclass="identifier">optional</span><spanclass="special"><</span><spanclass="identifier">T</span><spanclass="special">&></span></code>
Copies of <codeclass="computeroutput"><spanclass="identifier">optional</span><spanclass="special"><</span><spanclass="identifier">T</span><spanclass="special">&></span></code>
will copy the references but all these references will nonetheless reefer
will copy the references but all these references will nonetheless reefer
to the same object.
to the same object.
</li>
</li>
<li>
<liclass="listitem">
Value-access will actually provide access to the referenced object rather
Value-access will actually provide access to the referenced object rather
<aname="boost_optional.rebinding_semantics_for_assignment_of_optional_references"></a><aclass="link"href="rebinding_semantics_for_assignment_of_optional_references.html"title="Rebinding semantics for assignment of optional references">Rebinding
<aname="boost_optional.rebinding_semantics_for_assignment_of_optional_references"></a><aclass="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>
semantics for assignment of optional references</a>
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