124 lines
14 KiB
HTML
124 lines
14 KiB
HTML
<html>
|
||
<head>
|
||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
|
||
<title>Macro BOOST_CONTRACT_OLD_PTR</title>
|
||
<link rel="stylesheet" href="../../../../doc/src/boostbook.css" type="text/css">
|
||
<meta name="generator" content="DocBook XSL Stylesheets V1.79.1">
|
||
<link rel="home" href="index.html" title="Chapter 1. Boost.Contract 1.0.0">
|
||
<link rel="up" href="reference.html#header.boost.contract_macro_hpp" title="Header <boost/contract_macro.hpp>">
|
||
<link rel="prev" href="BOOST_CONTRACT_OLD.html" title="Macro BOOST_CONTRACT_OLD">
|
||
<link rel="next" href="BOOST_CO_idm45028038671712.html" title="Macro BOOST_CONTRACT_OLD_PTR_IF_COPYABLE">
|
||
</head>
|
||
<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
|
||
<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="../../../../libs/libraries.htm">Libraries</a></td>
|
||
<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>
|
||
<div class="spirit-nav">
|
||
<a accesskey="p" href="BOOST_CONTRACT_OLD.html"><img src="../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="reference.html#header.boost.contract_macro_hpp"><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="BOOST_CO_idm45028038671712.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a>
|
||
</div>
|
||
<div class="refentry">
|
||
<a name="BOOST_CONTRACT_OLD_PTR"></a><div class="titlepage"></div>
|
||
<div class="refnamediv">
|
||
<h2><span class="refentrytitle">Macro BOOST_CONTRACT_OLD_PTR</span></h2>
|
||
<p>BOOST_CONTRACT_OLD_PTR — Program old values that can be completely disabled at compile-time for old value types that are required to be copyable. </p>
|
||
</div>
|
||
<h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2>
|
||
<div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: <<a class="link" href="reference.html#header.boost.contract_macro_hpp" title="Header <boost/contract_macro.hpp>">boost/contract_macro.hpp</a>>
|
||
|
||
</span>BOOST_CONTRACT_OLD_PTR(...)</pre></div>
|
||
<div class="refsect1">
|
||
<a name="idm45909316703088"></a><h2>Description</h2>
|
||
<p>This is used to program old value copies for copyable types:</p>
|
||
<pre class="programlisting"><span class="keyword">class</span> <span class="identifier">u</span> <span class="special">{</span>
|
||
<span class="keyword">public</span><span class="special">:</span>
|
||
<span class="keyword">void</span> <span class="identifier">f</span><span class="special">(</span><span class="special">...</span><span class="special">)</span> <span class="special">{</span>
|
||
<span class="identifier">BOOST_CONTRACT_OLD_PTR</span><span class="special">(</span><span class="identifier">old_type_a</span><span class="special">)</span><span class="special">(</span><span class="identifier">old_var_a</span><span class="special">)</span><span class="special">;</span> <span class="comment">// Null...</span>
|
||
<span class="identifier">BOOST_CONTRACT_OLD_PTR</span><span class="special">(</span><span class="identifier">old_type_b</span><span class="special">)</span><span class="special">(</span><span class="identifier">old_var_b</span><span class="special">,</span> <span class="identifier">old_expr_b</span><span class="special">)</span><span class="special">;</span> <span class="comment">// Set.</span>
|
||
<span class="identifier">BOOST_CONTRACT_PUBLIC_FUNCTION</span><span class="special">(</span><span class="keyword">this</span><span class="special">)</span>
|
||
<span class="special">...</span>
|
||
<span class="identifier">BOOST_CONTRACT_OLD</span><span class="special">(</span><span class="special">[</span><span class="special">&</span><span class="special">]</span> <span class="special">{</span>
|
||
<span class="identifier">old_var_a</span> <span class="special">=</span> <span class="identifier">BOOST_CONTRACT_OLDOF</span><span class="special">(</span><span class="identifier">old_expr_a</span><span class="special">)</span><span class="special">;</span> <span class="comment">// ...set.</span>
|
||
<span class="special">...</span>
|
||
<span class="special">}</span><span class="special">)</span>
|
||
<span class="special">...</span>
|
||
<span class="special">;</span>
|
||
|
||
<span class="special">...</span> <span class="comment">// Function body.</span>
|
||
<span class="special">}</span>
|
||
|
||
<span class="keyword">virtual</span> <span class="keyword">void</span> <span class="identifier">g</span><span class="special">(</span><span class="special">...</span><span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">contract</span><span class="special">::</span><span class="identifier">virtual_</span><span class="special">*</span> <span class="identifier">v</span> <span class="special">=</span> <span class="number">0</span><span class="special">)</span> <span class="special">{</span>
|
||
<span class="identifier">BOOST_CONTRACT_OLD_PTR</span><span class="special">(</span><span class="identifier">old_type_a</span><span class="special">)</span><span class="special">(</span><span class="identifier">old_var_a</span><span class="special">)</span><span class="special">;</span> <span class="comment">// No `v`</span>
|
||
<span class="identifier">BOOST_CONTRACT_OLD_PTR</span><span class="special">(</span><span class="identifier">old_type_b</span><span class="special">)</span><span class="special">(</span><span class="identifier">v</span><span class="special">,</span> <span class="identifier">old_var_b</span><span class="special">,</span> <span class="identifier">old_expr_b</span><span class="special">)</span><span class="special">;</span> <span class="comment">// `v`</span>
|
||
<span class="identifier">BOOST_CONTRACT_PUBLIC_FUNCTION</span><span class="special">(</span><span class="identifier">v</span><span class="special">,</span> <span class="keyword">this</span><span class="special">)</span>
|
||
<span class="special">...</span>
|
||
<span class="identifier">BOOST_CONTRACT_OLD</span><span class="special">(</span><span class="special">[</span><span class="special">&</span><span class="special">]</span> <span class="special">{</span>
|
||
<span class="identifier">old_var_a</span> <span class="special">=</span> <span class="identifier">BOOST_CONTRACT_OLDOF</span><span class="special">(</span><span class="identifier">v</span><span class="special">,</span> <span class="identifier">old_expr_a</span><span class="special">)</span><span class="special">;</span> <span class="comment">// `v`</span>
|
||
<span class="special">...</span>
|
||
<span class="special">}</span><span class="special">)</span>
|
||
<span class="special">...</span>
|
||
<span class="special">;</span>
|
||
|
||
<span class="special">...</span> <span class="comment">// Function body.</span>
|
||
<span class="special">}</span>
|
||
|
||
<span class="special">...</span>
|
||
<span class="special">}</span><span class="special">;</span>
|
||
</pre>
|
||
<p>This is an overloaded variadic macro and it can be used in the following different ways (note that no code is generated when <code class="computeroutput"><a class="link" href="BOOST_CONTRACT_NO_OLDS.html" title="Macro BOOST_CONTRACT_NO_OLDS">BOOST_CONTRACT_NO_OLDS</a></code> is defined).</p>
|
||
<p>1. <code class="computeroutput">BOOST_CONTRACT_OLD_PTR(old_type)(old_var)</code> expands to code equivalent to the following (this leaves the old value pointer null):</p>
|
||
<pre class="programlisting"><span class="preprocessor">#ifndef</span> <span class="identifier">BOOST_CONTRACT_NO_OLDS</span>
|
||
<span class="comment">// This declaration does not need to use `v`.</span>
|
||
<span class="identifier">boost</span><span class="special">::</span><span class="identifier">contract</span><span class="special">::</span><span class="identifier">old_ptr</span><span class="special"><</span><span class="identifier">old_type</span><span class="special">></span> <span class="identifier">old_var</span>
|
||
<span class="preprocessor">#endif</span>
|
||
</pre>
|
||
<p>2. <code class="computeroutput">BOOST_CONTRACT_OLD_PTR(old_type)(old_var, old_expr)</code> expands to code equivalent to the following (this initializes the pointer to the old value copy, but not to be used for virtual public functions and public function overrides):</p>
|
||
<pre class="programlisting"><span class="preprocessor">#ifndef</span> <span class="identifier">BOOST_CONTRACT_NO_OLDS</span>
|
||
<span class="identifier">boost</span><span class="special">::</span><span class="identifier">contract</span><span class="special">::</span><span class="identifier">old_ptr</span><span class="special"><</span><span class="identifier">old_type</span><span class="special">></span> <span class="identifier">old_var</span> <span class="special">=</span>
|
||
<span class="identifier">BOOST_CONTRACT_OLDOF</span><span class="special">(</span><span class="identifier">old_expr</span><span class="special">)</span>
|
||
<span class="preprocessor">#endif</span>
|
||
</pre>
|
||
<p>3. <code class="computeroutput">BOOST_CONTRACT_OLD_PTR(old_type)(v, old_var, old_expr)</code> expands to code equivalent to the following (this initializes the pointer to the old value copy for virtual public functions and public function overrides):</p>
|
||
<pre class="programlisting"><span class="preprocessor">#ifndef</span> <span class="identifier">BOOST_CONTRACT_NO_OLDS</span>
|
||
<span class="identifier">boost</span><span class="special">::</span><span class="identifier">contract</span><span class="special">::</span><span class="identifier">old_ptr</span><span class="special"><</span><span class="identifier">old_type</span><span class="special">></span> <span class="identifier">old_var</span> <span class="special">=</span>
|
||
<span class="identifier">BOOST_CONTRACT_OLDOF</span><span class="special">(</span><span class="identifier">v</span><span class="special">,</span> <span class="identifier">old_expr</span><span class="special">)</span>
|
||
<span class="preprocessor">#endif</span>
|
||
</pre>
|
||
<p>Where:</p>
|
||
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
|
||
<li class="listitem"><p><code class="computeroutput"><span class="bold"><strong>old_type</strong></span></code> is the type of the pointed old value. This type must be copyable (i.e., <code class="computeroutput">boost::contract::is_old_value_copyable<old_type>::value</code> is <code class="computeroutput">true</code>), otherwise this pointer will always be null and this library will generate a compile-time error when the pointer is dereferenced (see <code class="computeroutput"><a class="link" href="BOOST_CO_idm45028038671712.html" title="Macro BOOST_CONTRACT_OLD_PTR_IF_COPYABLE">BOOST_CONTRACT_OLD_PTR_IF_COPYABLE</a></code>). (This is a variadic macro parameter so it can contain commas not protected by round parenthesis.) (Rationale: Template parameters like this one are specified to this library macro interface using their own set of parenthesis <code class="computeroutput">SOME_MACRO(template_params)(other_params)</code>.) </p></li>
|
||
<li class="listitem"><p><code class="computeroutput"><span class="bold"><strong>v</strong></span></code> is the extra training parameter of type <code class="computeroutput"><a class="link" href="boost/contract/virtual_.html" title="Class virtual_">boost::contract::virtual_</a></code><code class="computeroutput">*</code> and default value <code class="computeroutput">0</code> from the enclosing virtual public function or public function override declaring the contract. (This is not a variadic macro parameter but it should never contain commas because it is an identifier.) </p></li>
|
||
<li class="listitem"><p><code class="computeroutput"><span class="bold"><strong>old_var</strong></span></code> is the name of the old value pointer variable. (This is not a variadic macro parameter but it should never contain commas because it is an identifier.) </p></li>
|
||
<li class="listitem"><p><code class="computeroutput"><span class="bold"><strong>old_expr</strong></span></code> is the expression to be evaluated and copied in the old value pointer. (This is not a variadic macro parameter so any comma it might contain must be protected by round parenthesis and <code class="computeroutput">BOOST_CONTRACT_OLD_PTR(old_type)(v, old_var, (old_expr))</code> will always work.)</p></li>
|
||
</ul></div>
|
||
<p>
|
||
</p>
|
||
<p><span class="bold"><strong>See Also:</strong></span></p>
|
||
<p> <a class="link" href="boost_contract/extras.html#boost_contract.extras.disable_contract_compilation__macro_interface_" title="Disable Contract Compilation (Macro Interface)">
|
||
Disable Contract Compilation</a>, <a class="link" href="boost_contract/tutorial.html#boost_contract.tutorial.old_values" title="Old Values"> Old Values</a> </p>
|
||
<p>
|
||
</p>
|
||
<p>
|
||
</p>
|
||
</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 © 2008-2019 Lorenzo Caminiti<p>
|
||
Distributed under the Boost Software License, Version 1.0 (see accompanying
|
||
file LICENSE_1_0.txt or a copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
|
||
</p>
|
||
</div></td>
|
||
</tr></table>
|
||
<hr>
|
||
<div class="spirit-nav">
|
||
<a accesskey="p" href="BOOST_CONTRACT_OLD.html"><img src="../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="reference.html#header.boost.contract_macro_hpp"><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="BOOST_CO_idm45028038671712.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a>
|
||
</div>
|
||
</body>
|
||
</html>
|