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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]
162 lines
4.8 KiB
HTML
162 lines
4.8 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<html>
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<head>
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<meta http-equiv="Content-Language" content="en-us">
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<meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
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<title>Boost Function Object Adapter Library</title>
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</head>
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<body bgcolor="#FFFFFF" text="#000000">
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<table border="1" bgcolor="#007F7F" cellpadding="2" summary="">
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<tr>
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<td bgcolor="#FFFFFF"><img src="../../boost.png" alt=
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"boost.png (6897 bytes)" width="277" height="86"></td>
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<td><a href="../../index.htm"><font face="Arial" color=
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"#FFFFFF"><big>Home</big></font></a></td>
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<td><a href="../libraries.htm"><font face="Arial" color=
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"#FFFFFF"><big>Libraries</big></font></a></td>
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<td><a href="../../people/people.htm"><font face="Arial" color=
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"#FFFFFF"><big>People</big></font></a></td>
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<td><a href="../../more/faq.htm"><font face="Arial" color=
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"#FFFFFF"><big>FAQ</big></font></a></td>
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<td><a href="../../more/index.htm"><font face="Arial" color=
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"#FFFFFF"><big>More</big></font></a></td>
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</tr>
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</table>
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<h1>Binders</h1>
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<p>The header <a href="../../boost/functional.hpp">functional.hpp</a>
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provides enhanced versions of both the binder function object adapters from
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the C++ Standard Library (§20.3.6):</p>
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<ul>
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<li><tt>binder1st</tt></li>
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<li><tt>binder2nd</tt></li>
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</ul>
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<p>As well as the corresponding helper functions</p>
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<ul>
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<li><tt>bind1st</tt></li>
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<li><tt>bind2nd</tt></li>
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</ul>
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<p>The key benefit of these adapters over those in the Standard Library is
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they avoid the problem of <a href="#refref">references to
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references.</a></p>
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<h3>Usage</h3>
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<p>Usage is identical to the standard binders. For example,</p>
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<blockquote>
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<pre>
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class Foo {
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public:
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void bar(std::ostream &);
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// ...
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};
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// ...
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std::vector<Foo> c;
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// ...
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std::for_each(c.begin(), c.end(),
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boost::bind2nd(boost::mem_fun_ref(&Foo::bar), std::cout));
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</pre>
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</blockquote>
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<h3 id="refref">References to References</h3>
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<p>Consider the usage example above</p>
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<blockquote>
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<pre>
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class Foo {
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public:
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void bar(<strong>std::ostream &</strong>);
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// ...
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};
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// ...
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std::for_each(c.begin(), c.end(),
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boost::bind2nd(boost::mem_fun_ref(&Foo::bar), std::cout));
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</pre>
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</blockquote>
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<p>If this had been written using <tt>std::bind2nd</tt> and
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<tt>std::mem_fun_ref</tt>, it would be unlikely to compile.</p>
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<p>The problem arises because <tt>bar</tt> takes a reference argument. The
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Standard defines <tt>std::mem_fun_ref</tt> such that it creates a function
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object whose <tt>second_argument_type</tt> will be
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<tt>std::ostream&</tt>.</p>
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<p>The call to <tt>bind2nd</tt> creates a <tt>binder2nd</tt> which the
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Standard defines as follows:</p>
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<blockquote>
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<pre>
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template <class Operation>
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class binder2nd
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: public unary_function<typename Operation::first_argument_type,
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typename Operation::result_type> {
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...
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public:
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binder2nd(const Operation& x,
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<strong>const typename Operation::second_argument_type& y</strong>);
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...
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</pre>
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</blockquote>
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<p>Since our operation's <tt>second_argument_type</tt> is
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<tt>std::ostream&</tt>, the type of <tt>y</tt> in the constructor would
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be <tt>std::ostream&&</tt>. Since you cannot have a reference to a
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reference, at this point we should get a compilation error because
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references to references are illegal in C++ (but see <a href=
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"http://anubis.dkuug.dk/jtc1/sc22/wg21/docs/cwg_active.html#106">C++
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Standard core language active issues list</a>).</p>
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<p>The binders in this library avoid this problem by using the Boost
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<tt><a href="../utility/call_traits.htm">call_traits</a></tt>
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templates.</p>
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<p>Our constructor is declared</p>
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<blockquote>
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<pre>
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binder2nd(const Operation& x,
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<strong>typename call_traits<
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typename binary_traits<Operation>::second_argument_type
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>::param_type y</strong>)
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</pre>
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</blockquote>
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<p>As a result, <tt>y</tt> has a type of <tt>std::ostream&</tt>, and
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our example compiles.</p>
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<hr>
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<p><a href="http://validator.w3.org/check?uri=referer"><img border="0" src=
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"http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01 Transitional"
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height="31" width="88"></a></p>
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<p>Revised
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<!--webbot bot="Timestamp" s-type="EDITED" s-format="%d %B, %Y" startspan -->02
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December, 2006<!--webbot bot="Timestamp" endspan i-checksum="38510" --></p>
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<p><i>Copyright © 2000 Cadenza New Zealand Ltd.</i></p>
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<p><i>Distributed under the Boost Software License, Version 1.0. (See
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accompanying file <a href="../../LICENSE_1_0.txt">LICENSE_1_0.txt</a> or
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copy at <a href=
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"http://www.boost.org/LICENSE_1_0.txt">http://www.boost.org/LICENSE_1_0.txt</a>)</i></p>
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</body>
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</html>
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