mirror of
https://github.com/boostorg/functional.git
synced 2026-01-25 16:32:29 +01:00
792ee1fee1
From Mark Rodgers Fri Dec 1 12:59:14 2006 X-Apparently-To: ahd6974-boostorg -at- yahoo.com via 68.142.206.160; Fri, 01 Dec 2006 12:59:41 -0800 X-Originating-IP: [195.112.4.54] Return-Path: <mark.rodgers -at- cadenza.co.nz> Authentication-Results: mta550.mail.mud.yahoo.com from=cadenza.co.nz; domainkeys=neutral (no sig) Received: from 195.112.4.54 (EHLO smtp.nildram.co.uk) (195.112.4.54) by mta550.mail.mud.yahoo.com with SMTP; Fri, 01 Dec 2006 12:59:40 -0800 Received: from snagglepuss.cadenza.co.nz (81-6-246-87.dyn.gotadsl.co.uk [81.6.246.87]) by smtp.nildram.co.uk (Postfix) with ESMTP id D32EA2B6D8C for <ahd6974-boostorg -at- yahoo.com>; Fri, 1 Dec 2006 20:59:35 +0000 (GMT) Received: from penfold.cadenza.co.nz ([192.168.55.56]) by snagglepuss.cadenza.co.nz with esmtp (Exim 4.63) (envelope-from <mark.rodgers -at- cadenza.co.nz>) id J9M4Y9-0009TO-9K for ahd6974-boostorg -at- yahoo.com; Fri, 01 Dec 2006 20:58:57 +0000 Message-ID: <457097A2.1090305@cadenza.co.nz> Date: Fri, 01 Dec 2006 20:59:14 +0000 From: "Mark Rodgers" <mark.rodgers -at- cadenza.co.nz> User-Agent: Thunderbird 1.5.0.8 (Macintosh/20061025) MIME-Version: 1.0 To: ahd6974-boostorg -at- yahoo.com [Edit - Delete] Subject: Re: [boost] Reminder: Need your permission to correct license & copyright issues References: <379990.36007.qm@web33507.mail.mud.yahoo.com> In-Reply-To: <379990.36007.qm@web33507.mail.mud.yahoo.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Length: 812 Gidday Andreas Sure that's fine. I'm happy for you to do 1, 2 and 3. Regards Mark Andreas Huber wrote: > Hello Mark > > Quite a while ago it was decided that every file that goes into the > 1.34 release of the Boost distribution (www.boost.org) needs uniform > license and copyright information. For more information please see: > > <http://www.boost.org/more/license_info.html> > > You are receiving this email because several files you contributed > lack such information or have an old license: > > boost/functional/functional.hpp > boost/libs/functional/binders.html > boost/libs/functional/function_test.cpp > boost/libs/functional/function_traits.html > boost/libs/functional/index.html > boost/libs/functional/mem_fun.html > boost/libs/functional/negators.html > boost/libs/functional/ptr_fun.html > boost/people/mark_rodgers.htm > > I therefore kindly ask you to grant the permission to do the > following: > > 1. For the files above that already have a license text (all except > mark_rodgers.htm), replace the license text with: > > "Distributed under the Boost Software License, Version 1.0. (See > accompanying file LICENSE_1_0.txt or copy at > http://www.boost.org/LICENSE_1_0.txt)" > > 2. For the file that does not yet have a license and copyright > (mark_rodgers.htm) add the same license text as under 1. and add the > following copyright: > > "(c) Copyright Mark Rodgers 2000" > > 3. (Optional) I would also want to convert all HTML files to conform > the HTML 4.01 Standard by running them through HTML Tidy, see > <http://tidy.sf.net> > > It would be great if you could grant me permission to do 1 & 2 and > optionally also 3. > > Thank you! > > Regards, > > Andreas Huber > [SVN r36245]
159 lines
5.5 KiB
HTML
159 lines
5.5 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
|
|
|
|
<html>
|
|
<head>
|
|
<meta http-equiv="Content-Language" content="en-us">
|
|
<meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
|
|
|
|
<title>Boost Function Object Adapter Library</title>
|
|
</head>
|
|
|
|
<body bgcolor="#FFFFFF" text="#000000">
|
|
<table border="1" bgcolor="#007F7F" cellpadding="2" summary="">
|
|
<tr>
|
|
<td bgcolor="#FFFFFF"><img src="../../boost.png" alt=
|
|
"boost.png (6897 bytes)" width="277" height="86"></td>
|
|
|
|
<td><a href="../../index.htm"><font face="Arial" color=
|
|
"#FFFFFF"><big>Home</big></font></a></td>
|
|
|
|
<td><a href="../libraries.htm"><font face="Arial" color=
|
|
"#FFFFFF"><big>Libraries</big></font></a></td>
|
|
|
|
<td><a href="../../people/people.htm"><font face="Arial" color=
|
|
"#FFFFFF"><big>People</big></font></a></td>
|
|
|
|
<td><a href="../../more/faq.htm"><font face="Arial" color=
|
|
"#FFFFFF"><big>FAQ</big></font></a></td>
|
|
|
|
<td><a href="../../more/index.htm"><font face="Arial" color=
|
|
"#FFFFFF"><big>More</big></font></a></td>
|
|
</tr>
|
|
</table>
|
|
|
|
<h1>Negators</h1>
|
|
|
|
<p>The header <a href="../../boost/functional.hpp">functional.hpp</a>
|
|
provides enhanced versions of both the negator adapters from the C++
|
|
Standard Library (§20.3.5):</p>
|
|
|
|
<ul>
|
|
<li><tt>unary_negate</tt></li>
|
|
|
|
<li><tt>binary_negate</tt></li>
|
|
</ul>
|
|
|
|
<p>As well as the corresponding helper functions</p>
|
|
|
|
<ul>
|
|
<li><tt>not1</tt></li>
|
|
|
|
<li><tt>not2</tt></li>
|
|
</ul>
|
|
|
|
<p>However, the negators in this library improve on the standard versions
|
|
in two ways:</p>
|
|
|
|
<ul>
|
|
<li>They use <a href="function_traits.html">function object traits</a> to
|
|
avoid the need for <tt>ptr_fun</tt> when negating a function rather than
|
|
an adaptable function object.</li>
|
|
|
|
<li>They use Boost <a href=
|
|
"../utility/call_traits.htm">call traits</a> to determine the best
|
|
way to declare their arguments and pass them through to the adapted
|
|
function (see <a href="#arguments">below</a>).</li>
|
|
</ul>
|
|
|
|
<h3>Usage</h3>
|
|
|
|
<p>Usage is identical to the standard negators. For example,</p>
|
|
|
|
<blockquote>
|
|
<pre>
|
|
bool bad(const Foo &foo) { ... }
|
|
...
|
|
std::vector<Foo> c;
|
|
...
|
|
std::find_if(c.begin(), c.end(), boost::not1(bad));
|
|
</pre>
|
|
</blockquote>
|
|
|
|
<h3 id="arguments">Argument Types</h3>
|
|
|
|
<p>The C++ Standard (§20.3.5) defines unary negate like this (binary
|
|
negate is similar):</p>
|
|
|
|
<blockquote>
|
|
<pre>
|
|
template <class Predicate>
|
|
class unary_negate
|
|
: public unary_function<typename Predicate::argument_type,bool> {
|
|
public:
|
|
explicit unary_negate(const Predicate& pred);
|
|
bool operator()(<strong>const typename Predicate::argument_type&</strong> x) const;
|
|
};
|
|
</pre>
|
|
</blockquote>
|
|
|
|
<p>Note that if the Predicate's <tt>argument_type</tt> is a reference, the
|
|
type of <tt>operator()</tt>'s argument would be a reference to a reference.
|
|
Currently this is illegal in C++ (but see the <a href=
|
|
"http://anubis.dkuug.dk/jtc1/sc22/wg21/docs/cwg_active.html#106">C++
|
|
standard core language active issues list</a>).</p>
|
|
|
|
<p>However, if we instead defined <tt>operator()</tt> to accept Predicate's
|
|
argument_type unmodified, this would be needlessly inefficient if it were a
|
|
value type; the argument would be copied twice - once when calling
|
|
<tt>unary_negate</tt>'s <tt>operator()</tt>, and again when
|
|
<tt>operator()</tt> called the adapted function.</p>
|
|
|
|
<p>So how we want to declare the argument for <tt>operator()</tt> depends
|
|
on whether or not the Predicate's <tt>argument_type</tt> is a reference. If
|
|
it is a reference, we want to declare it simply as <tt>argument_type</tt>;
|
|
if it is a value we want to declare it as
|
|
<tt>const argument_type&</tt>.</p>
|
|
|
|
<p>The Boost <a href="../utility/call_traits.htm">call_traits</a> class
|
|
template contains a <tt>param_type</tt> typedef, which uses partial
|
|
specialisation to make precisely this decision. If we were to declare
|
|
<tt>operator()</tt> as</p>
|
|
|
|
<blockquote>
|
|
<pre>
|
|
bool operator()(typename call_traits<typename Predicate::argument_type>::param_type x) const
|
|
</pre>
|
|
</blockquote>
|
|
|
|
<p>the desired result would be achieved - we would eliminate references to
|
|
references without loss of efficiency. In fact, the actual declaration is
|
|
slightly more complicated because of the use of function object traits, but
|
|
the effect remains the same.</p>
|
|
|
|
<h3>Limitations</h3>
|
|
|
|
<p>Both the function object traits and call traits used to realise these
|
|
improvements rely on partial specialisation, these improvements are only
|
|
available on compilers that support that feature. With other compilers, the
|
|
negators in this library behave very much like those in the Standard -
|
|
<tt>ptr_fun</tt> will be required to adapt functions, and references to
|
|
references will not be avoided.</p>
|
|
<hr>
|
|
|
|
<p><a href="http://validator.w3.org/check?uri=referer"><img border="0" src=
|
|
"http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01 Transitional"
|
|
height="31" width="88"></a></p>
|
|
|
|
<p>Revised
|
|
<!--webbot bot="Timestamp" s-type="EDITED" s-format="%d %B, %Y" startspan -->02
|
|
December, 2006<!--webbot bot="Timestamp" endspan i-checksum="38510" --></p>
|
|
|
|
<p><i>Copyright © 2000 Cadenza New Zealand Ltd.</i></p>
|
|
|
|
<p><i>Distributed under the Boost Software License, Version 1.0. (See
|
|
accompanying file <a href="../../LICENSE_1_0.txt">LICENSE_1_0.txt</a> or
|
|
copy at <a href=
|
|
"http://www.boost.org/LICENSE_1_0.txt">http://www.boost.org/LICENSE_1_0.txt</a>)</i></p>
|
|
</body>
|
|
</html>
|