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  28 <h2><span class="refentrytitle">Macro BOOST_CONTRACT_PUBLIC_FUNCTION</span></h2>
  29 <p>BOOST_CONTRACT_PUBLIC_FUNCTION &#8212; Program contracts that can be completely disabled at compile-time for non-static 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_macro_hpp" title="Header &lt;boost/contract_macro.hpp&gt;">boost/contract_macro.hpp</a>&gt;
  33
  34 </span>BOOST_CONTRACT_PUBLIC_FUNCTION(...)</pre></div>
  35 <div class="refsect1">
  36 <a name="idm45751725652704"></a><h2>Description</h2>
  37 <p>This is used together with <code class="computeroutput"><a class="link" href="BOOST_CO_idm45123869622736.html" title="Macro BOOST_CONTRACT_PRECONDITION">BOOST_CONTRACT_PRECONDITION</a></code>,  <code class="computeroutput"><a class="link" href="BOOST_CO_idm45123869611056.html" title="Macro BOOST_CONTRACT_POSTCONDITION">BOOST_CONTRACT_POSTCONDITION</a></code>, <code class="computeroutput"><a class="link" href="BOOST_CONTRACT_EXCEPT.html" title="Macro BOOST_CONTRACT_EXCEPT">BOOST_CONTRACT_EXCEPT</a></code>, and <code class="computeroutput"><a class="link" href="BOOST_CONTRACT_OLD.html" title="Macro BOOST_CONTRACT_OLD">BOOST_CONTRACT_OLD</a></code> to specify preconditions, postconditions, exception guarantees, and old value copies at body that can be completely disabled at compile-time for non-static public functions (virtual or not, void or not) that do not override:</p>
  38 <pre class="programlisting"><span class="keyword">class</span> <span class="identifier">u</span> <span class="special">{</span>
  39     <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>
  40
  41     <span class="identifier">BOOST_CONTRACT_INVARIANT</span><span class="special">(</span><span class="special">{</span> <span class="comment">// Optional (as for static and volatile).</span>
  42         <span class="identifier">BOOST_CONTRACT_ASSERT</span><span class="special">(</span><span class="special">...</span><span class="special">)</span><span class="special">;</span>
  43         <span class="special">...</span>
  44     <span class="special">}</span><span class="special">)</span>
  45
  46 <span class="keyword">public</span><span class="special">:</span>
  47     <span class="comment">// Non-virtual (same if void).</span>
  48     <span class="identifier">t</span> <span class="identifier">f</span><span class="special">(</span><span class="special">...</span><span class="special">)</span> <span class="special">{</span>
  49         <span class="identifier">t</span> <span class="identifier">result</span><span class="special">;</span>
  50         <span class="identifier">BOOST_CONTRACT_OLD_PTR</span><span class="special">(</span><span class="identifier">old_type</span><span class="special">)</span><span class="special">(</span><span class="identifier">old_var</span><span class="special">)</span><span class="special">;</span>
  51         <span class="identifier">BOOST_CONTRACT_PUBLIC_FUNCTION</span><span class="special">(</span><span class="keyword">this</span><span class="special">)</span>
  52             <span class="identifier">BOOST_CONTRACT_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>
  53                 <span class="identifier">BOOST_CONTRACT_ASSERT</span><span class="special">(</span><span class="special">...</span><span class="special">)</span><span class="special">;</span>
  54                 <span class="special">...</span>
  55             <span class="special">}</span><span class="special">)</span>
  56             <span class="identifier">BOOST_CONTRACT_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>
  57                 <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="special">;</span>
  58                 <span class="special">...</span>
  59             <span class="special">}</span><span class="special">)</span>
  60             <span class="identifier">BOOST_CONTRACT_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>
  61                 <span class="identifier">BOOST_CONTRACT_ASSERT</span><span class="special">(</span><span class="special">...</span><span class="special">)</span><span class="special">;</span>
  62                 <span class="special">...</span>
  63             <span class="special">}</span><span class="special">)</span>
  64             <span class="identifier">BOOST_CONTRACT_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>
  65                 <span class="identifier">BOOST_CONTRACT_ASSERT</span><span class="special">(</span><span class="special">...</span><span class="special">)</span><span class="special">;</span>
  66                 <span class="special">...</span>
  67             <span class="special">}</span><span class="special">)</span>
  68         <span class="special">;</span>
  69
  70         <span class="special">...</span> <span class="comment">// Function body (use `return result = return_expr`).</span>
  71     <span class="special">}</span>
  72
  73     <span class="comment">// Virtual and void.</span>
  74     <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>
  75         <span class="identifier">BOOST_CONTRACT_OLD_PTR</span><span class="special">(</span><span class="identifier">old_type</span><span class="special">)</span><span class="special">(</span><span class="identifier">old_var</span><span class="special">)</span><span class="special">;</span>
  76         <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>
  77             <span class="special">...</span>
  78             <span class="identifier">BOOST_CONTRACT_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>
  79                 <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>
  80                 <span class="special">...</span>
  81             <span class="special">}</span><span class="special">)</span>
  82             <span class="special">...</span>
  83         <span class="special">;</span>
  84
  85         <span class="special">...</span> <span class="comment">// Function body.</span>
  86     <span class="special">}</span>
  87
  88     <span class="comment">// Virtual and non-void.</span>
  89     <span class="keyword">virtual</span> <span class="identifier">t</span> <span class="identifier">h</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>
  90         <span class="identifier">t</span> <span class="identifier">result</span><span class="special">;</span>
  91         <span class="identifier">BOOST_CONTRACT_OLD_PTR</span><span class="special">(</span><span class="identifier">old_type</span><span class="special">)</span><span class="special">(</span><span class="identifier">old_var</span><span class="special">)</span><span class="special">;</span>
  92         <span class="identifier">BOOST_CONTRACT_PUBLIC_FUNCTION</span><span class="special">(</span><span class="identifier">v</span><span class="special">,</span> <span class="identifier">result</span><span class="special">,</span> <span class="keyword">this</span><span class="special">)</span>
  93             <span class="special">...</span>
  94             <span class="identifier">BOOST_CONTRACT_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>
  95                 <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>
  96                 <span class="special">...</span>
  97             <span class="special">}</span><span class="special">)</span>
  98             <span class="identifier">BOOST_CONTRACT_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="identifier">t</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">result</span><span class="special">)</span> <span class="special">{</span> <span class="comment">// Optional</span>
  99                 <span class="identifier">BOOST_CONTRACT_ASSERT</span><span class="special">(</span><span class="special">...</span><span class="special">)</span><span class="special">;</span>
 100                 <span class="special">...</span>
 101             <span class="special">}</span><span class="special">)</span>
 102             <span class="special">...</span>
 103         <span class="special">;</span>
 104
 105         <span class="special">...</span> <span class="comment">// Function body (use `return result = return_expr`).</span>
 106     <span class="special">}</span>
 107
 108     <span class="special">...</span>
 109 <span class="special">}</span><span class="special">;</span>
 110 </pre>
 111 <p>For optimization, this can be omitted for non-virtual public functions that do not have preconditions, postconditions and exception guarantees, within classes that have no invariants. Virtual public functions should always use  <code class="computeroutput"><a class="link" href="BOOST_CO_idm45123869395440.html" title="Macro BOOST_CONTRACT_PUBLIC_FUNCTION">BOOST_CONTRACT_PUBLIC_FUNCTION</a></code> otherwise this library will not be able to correctly use them for subcontracting.</p>
 112 <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_CO_idm45123870441776.html" title="Macro BOOST_CONTRACT_NO_PUBLIC_FUNCTIONS">BOOST_CONTRACT_NO_PUBLIC_FUNCTIONS</a></code> is defined).</p>
 113 <p>1. <code class="computeroutput">BOOST_CONTRACT_PUBLIC_FUNCTION(obj)</code> expands to code equivalent to the following (for non-virtual public functions that are not static and do not override, returning void or not):</p>
 114 <pre class="programlisting"><span class="preprocessor">#ifndef</span> <span class="identifier">BOOST_CONTRACT_NO_PUBLIC_FUNCTIONS</span>
 115     <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">internal_var</span> <span class="special">=</span>
 116             <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">obj</span><span class="special">)</span>
 117 <span class="preprocessor">#endif</span>
 118 </pre>
 119 <p>2. <code class="computeroutput">BOOST_CONTRACT_PUBLIC_FUNCTION(v, obj)</code> expands to code equivalent to the following (for virtual public functions that are not static and do not override, returning void):</p>
 120 <pre class="programlisting"><span class="preprocessor">#ifndef</span> <span class="identifier">BOOST_CONTRACT_NO_PUBLIC_FUNCTIONS</span>
 121     <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">internal_var</span> <span class="special">=</span>
 122             <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="identifier">obj</span><span class="special">)</span>
 123 <span class="preprocessor">#endif</span>
 124 </pre>
 125 <p>3. <code class="computeroutput">BOOST_CONTRACT_PUBLIC_FUNCTION(v, r, obj)</code> expands to code equivalent to the following (for virtual public functions that are not static and do not override, not returning void):</p>
 126 <pre class="programlisting"><span class="preprocessor">#ifndef</span> <span class="identifier">BOOST_CONTRACT_NO_PUBLIC_FUNCTIONS</span>
 127     <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">internal_var</span> <span class="special">=</span>
 128             <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="identifier">r</span><span class="special">,</span> <span class="identifier">obj</span><span class="special">)</span>
 129 <span class="preprocessor">#endif</span>
 130 </pre>
 131 <p>Where (these are all variadic macro parameters so they can contain commas not protected by round parenthesis):</p>
 132 <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
 133 <li class="listitem"><p><code class="computeroutput"><span class="bold"><strong>v</strong></span></code> is the extra 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 declaring the contract. </p></li>
 134 <li class="listitem"><p><code class="computeroutput"><span class="bold"><strong>r</strong></span></code> is a reference to the return value of the enclosing virtual public function declaring the contract. This is usually a local variable declared by the enclosing virtual public function just before the contract, but programmers must set it to the actual value being returned by the function at each <code class="computeroutput">return</code> statement. </p></li>
 135 <li class="listitem"><p><code class="computeroutput"><span class="bold"><strong>obj</strong></span></code> is the object <code class="computeroutput">this</code> from the scope of the enclosing 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">
 136         Volatile Public Functions</a>). </p></li>
 137 <li class="listitem"><p><code class="computeroutput"><span class="bold"><strong>internal_var</strong></span></code> is a variable name internally generated by this library (this name is unique but only on different line numbers so this macro cannot be expanded multiple times on the same line).</p></li>
 138 </ul></div>
 139 <p>
 140 </p>
 141 <p><span class="bold"><strong>See Also:</strong></span></p>
 142 <p> <a class="link" href="boost_contract/extras.html#boost_contract.extras.disable_contract_compilation__macro_interface_" title="Disable Contract Compilation (Macro Interface)">
 143         Disable Contract Compilation</a>,  <a class="link" href="boost_contract/tutorial.html#boost_contract.tutorial.public_functions" title="Public Functions"> Public Functions</a>,  <a class="link" href="boost_contract/tutorial.html#boost_contract.tutorial.virtual_public_functions" title="Virtual Public Functions">
 144         Virtual Public Functions</a> </p>
 145 <p>
 146 </p>
 147 <p>
 148 </p>
 149 </div>
 150 </div>
 151 <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
 152 <td align="left"></td>
 153 <td align="right"><div class="copyright-footer">Copyright &#169; 2008-2018 Lorenzo Caminiti<p>
 154         Distributed under the Boost Software License, Version 1.0 (see accompanying
 155         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>)
 156       </p>
 157 </div></td>
 158 </tr></table>
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