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  28 <h2><span class="refentrytitle">Function template public_function</span></h2>
  29 <p>boost::contract::public_function &#8212; Program contracts for void virtual public functions that do not override. </p>
  30 </div>
  31 <h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2>
  32 <div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: &lt;<a class="link" href="../../reference.html#header.boost.contract.public_function_hpp" title="Header &lt;boost/contract/public_function.hpp&gt;">boost/contract/public_function.hpp</a>&gt;
  33
  34 </span>
  35 <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> Class<span class="special">&gt;</span>
  36   <a class="link" href="specify__idm45394999179040.html" title="Class template specify_precondition_old_postcondition_except">specify_precondition_old_postcondition_except</a>
  37   <span class="identifier">public_function</span><span class="special">(</span><a class="link" href="virtual_.html" title="Class virtual_">virtual_</a> <span class="special">*</span> v<span class="special">,</span> <span class="identifier">Class</span> <span class="special">*</span> obj<span class="special">)</span><span class="special">;</span></pre></div>
  38 <div class="refsect1">
  39 <a name="idm45707993703312"></a><h2>Description</h2>
  40 <p>This is used to specify preconditions, postconditions, exception guarantees, old value copies at body, and check class invariants for public functions that are virtual, do not override, and return <code class="computeroutput">void:</code> </p>
  41 <pre class="programlisting"><span class="keyword">class</span> <span class="identifier">u</span> <span class="special">{</span>
  42     <span class="keyword">friend</span> <span class="keyword">class</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">contract</span><span class="special">::</span><span class="identifier">access</span><span class="special">;</span>
  43
  44     <span class="keyword">void</span> <span class="identifier">invariant</span><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span> <span class="special">{</span> <span class="comment">// Optional (as for static and volatile).</span>
  45         <span class="identifier">BOOST_CONTRACT_ASSERT</span><span class="special">(</span><span class="special">...</span><span class="special">)</span><span class="special">;</span>
  46         <span class="special">...</span>
  47     <span class="special">}</span>
  48
  49 <span class="keyword">public</span><span class="special">:</span>
  50     <span class="keyword">void</span> <span class="identifier">f</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>
  51         <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">&lt;</span><span class="identifier">old_type</span><span class="special">&gt;</span> <span class="identifier">old_var</span><span class="special">;</span>
  52         <span class="identifier">boost</span><span class="special">::</span><span class="identifier">contract</span><span class="special">::</span><span class="identifier">check</span> <span class="identifier">c</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">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>
  53             <span class="special">.</span><span class="identifier">precondition</span><span class="special">(</span><span class="special">[</span><span class="special">&amp;</span><span class="special">]</span> <span class="special">{</span> <span class="comment">// Optional.</span>
  54                 <span class="identifier">BOOST_CONTRACT_ASSERT</span><span class="special">(</span><span class="special">...</span><span class="special">)</span><span class="special">;</span>
  55                 <span class="special">...</span>
  56             <span class="special">}</span><span class="special">)</span>
  57             <span class="special">.</span><span class="identifier">old</span><span class="special">(</span><span class="special">[</span><span class="special">&amp;</span><span class="special">]</span> <span class="special">{</span> <span class="comment">// Optional.</span>
  58                 <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="special">;</span>
  59                 <span class="special">...</span>
  60             <span class="special">}</span><span class="special">)</span>
  61             <span class="special">.</span><span class="identifier">postcondition</span><span class="special">(</span><span class="special">[</span><span class="special">&amp;</span><span class="special">]</span> <span class="special">{</span> <span class="comment">// Optional.</span>
  62                 <span class="identifier">BOOST_CONTRACT_ASSERT</span><span class="special">(</span><span class="special">...</span><span class="special">)</span><span class="special">;</span>
  63                 <span class="special">...</span>
  64             <span class="special">}</span><span class="special">)</span>
  65             <span class="special">.</span><span class="identifier">except</span><span class="special">(</span><span class="special">[</span><span class="special">&amp;</span><span class="special">]</span> <span class="special">{</span> <span class="comment">// Optional.</span>
  66                 <span class="identifier">BOOST_CONTRACT_ASSERT</span><span class="special">(</span><span class="special">...</span><span class="special">)</span><span class="special">;</span>
  67                 <span class="special">...</span>
  68             <span class="special">}</span><span class="special">)</span>
  69         <span class="special">;</span>
  70
  71         <span class="special">...</span> <span class="comment">// Function body.</span>
  72     <span class="special">}</span>
  73
  74     <span class="special">...</span>
  75 <span class="special">}</span><span class="special">;</span>
  76 </pre>
  77 <p>A virtual public function should always call  <code class="computeroutput"><code class="computeroutput"><a class="link" href="public_f_idm45394998885120.html" title="Function template public_function">boost::contract::public_function</a></code></code> otherwise this library will not be able to correctly use it for subcontracting.</p>
  78 <p><span class="bold"><strong>See Also:</strong></span></p>
  79 <p> <a class="link" href="../../boost_contract/tutorial.html#boost_contract.tutorial.virtual_public_functions" title="Virtual Public Functions"> Virtual Public Functions</a></p>
  80 <p>
  81 </p>
  82 <p>
  83
  84
  85
  86 </p>
  87 <div class="variablelist"><table border="0" class="variablelist compact">
  88 <colgroup>
  89 <col align="left" valign="top">
  90 <col>
  91 </colgroup>
  92 <tbody>
  93 <tr>
  94 <td><p><span class="term">Parameters:</span></p></td>
  95 <td><div class="variablelist"><table border="0" class="variablelist compact">
  96 <colgroup>
  97 <col align="left" valign="top">
  98 <col>
  99 </colgroup>
 100 <tbody>
 101 <tr>
 102 <td><p><span class="term"><code class="computeroutput">obj</code></span></p></td>
 103 <td><p>The object <code class="computeroutput">this</code> from the scope of the enclosing virtual public function declaring the contract. This object might be mutable, <code class="computeroutput">const</code>, <code class="computeroutput">volatile</code>, or <code class="computeroutput">const volatile</code> depending on the cv-qualifier of the enclosing function (volatile public functions will check volatile class invariants, see  <a class="link" href="../../boost_contract/extras.html#boost_contract.extras.volatile_public_functions" title="Volatile Public Functions">
 104             Volatile Public Functions</a>).</p></td>
 105 </tr>
 106 <tr>
 107 <td><p><span class="term"><code class="computeroutput">v</code></span></p></td>
 108 <td><p>The trailing parameter of type  <code class="computeroutput"><code class="computeroutput"><a class="link" href="virtual_.html" title="Class virtual_">boost::contract::virtual_</a></code></code><code class="computeroutput">*</code> and default value <code class="computeroutput">0</code> from the enclosing virtual public function. </p></td>
 109 </tr>
 110 </tbody>
 111 </table></div></td>
 112 </tr>
 113 <tr>
 114 <td><p><span class="term">Template Parameters:</span></p></td>
 115 <td><div class="variablelist"><table border="0" class="variablelist compact">
 116 <colgroup>
 117 <col align="left" valign="top">
 118 <col>
 119 </colgroup>
 120 <tbody><tr>
 121 <td><p><span class="term"><code class="computeroutput">Class</code></span></p></td>
 122 <td><p>The type of the class containing the virtual public function declaring the contract. (Usually this template parameter is automatically deduced by C++ and it does not need to be explicitly specified by programmers.)</p></td>
 123 </tr></tbody>
 124 </table></div></td>
 125 </tr>
 126 <tr>
 127 <td><p><span class="term">Returns:</span></p></td>
 128 <td><p>The result of this function must be assigned to a variable of type  <code class="computeroutput"><a class="link" href="check.html" title="Class check">boost::contract::check</a></code> declared explicitly (i.e., without using C++11 <code class="computeroutput">auto</code> declarations) and locally just before the code of the public function body (otherwise this library will generate a run-time error, see  <code class="computeroutput"><a class="link" href="../../BOOST_CO_idm45394999694064.html" title="Macro BOOST_CONTRACT_ON_MISSING_CHECK_DECL">BOOST_CONTRACT_ON_MISSING_CHECK_DECL</a></code>). </p></td>
 129 </tr>
 130 </tbody>
 131 </table></div>
 132 </div>
 133 </div>
 134 <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
 135 <td align="left"></td>
 136 <td align="right"><div class="copyright-footer">Copyright &#169; 2008-2019 Lorenzo Caminiti<p>
 137         Distributed under the Boost Software License, Version 1.0 (see accompanying
 138         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>)
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