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  26 <a name="BOOST_CONTRACT_CONSTRUCTOR"></a><div class="titlepage"></div>
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  28 <h2><span class="refentrytitle">Macro BOOST_CONTRACT_CONSTRUCTOR</span></h2>
  29 <p>BOOST_CONTRACT_CONSTRUCTOR &#8212; Program contracts that can be completely disabled at compile-time for constructors. </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_CONSTRUCTOR(...)</pre></div>
  35 <div class="refsect1">
  36 <a name="idm45707992585824"></a><h2>Description</h2>
  37 <p>This is used together with <code class="computeroutput"><a class="link" href="BOOST_CO_idm45394998736528.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 postconditions, exception guarantees, and old value copies at body that can be completely disabled at compile-time for constructors (see  <code class="computeroutput"><a class="link" href="BOOST_CO_idm45394998587680.html" title="Macro BOOST_CONTRACT_CONSTRUCTOR_PRECONDITION">BOOST_CONTRACT_CONSTRUCTOR_PRECONDITION</a></code> to specify preconditions for constructors):</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="identifier">u</span><span class="special">(</span><span class="special">...</span><span class="special">)</span> <span class="special">{</span>
  48         <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>
  49         <span class="identifier">BOOST_CONTRACT_CONSTRUCTOR</span><span class="special">(</span><span class="keyword">this</span><span class="special">)</span>
  50             <span class="comment">// No `PRECONDITION` (use `CONSTRUCTOR_PRECONDITION` if needed).</span>
  51             <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>
  52                 <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_epxr</span><span class="special">)</span><span class="special">;</span>
  53                 <span class="special">...</span>
  54             <span class="special">}</span><span class="special">)</span>
  55             <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>
  56                 <span class="identifier">BOOST_CONTRACT_ASSERT</span><span class="special">(</span><span class="special">...</span><span class="special">)</span><span class="special">;</span>
  57                 <span class="special">...</span>
  58             <span class="special">}</span><span class="special">)</span>
  59             <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>
  60                 <span class="identifier">BOOST_CONTRACT_ASSERT</span><span class="special">(</span><span class="special">...</span><span class="special">)</span><span class="special">;</span>
  61                 <span class="special">...</span>
  62             <span class="special">}</span><span class="special">)</span>
  63         <span class="special">;</span> <span class="comment">// Trailing `;` is required.</span>
  64
  65         <span class="special">...</span> <span class="comment">// Constructor body.</span>
  66     <span class="special">}</span>
  67
  68     <span class="special">...</span>
  69 <span class="special">}</span><span class="special">;</span>
  70 </pre>
  71 <p>For optimization, this can be omitted for constructors that do not have postconditions and exception guarantees, within classes that have no invariants.</p>
  72 <p><code class="computeroutput">BOOST_CONTRACT_CONSTRUCTOR(obj)</code> expands to code equivalent to the following (note that no code is generated when  <code class="computeroutput"><a class="link" href="BOOST_CO_idm45394999605408.html" title="Macro BOOST_CONTRACT_NO_CONSTRUCTORS">BOOST_CONTRACT_NO_CONSTRUCTORS</a></code> is defined):</p>
  73 <pre class="programlisting"><span class="preprocessor">#ifndef</span> <span class="identifier">BOOST_CONTRACT_NO_CONSTRUCTORS</span>
  74     <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>
  75             <span class="identifier">boost</span><span class="special">::</span><span class="identifier">contract</span><span class="special">::</span><span class="identifier">constructor</span><span class="special">(</span><span class="identifier">obj</span><span class="special">)</span>
  76 <span class="preprocessor">#endif</span>
  77 </pre>
  78 <p>Where:</p>
  79 <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
  80 <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 constructor declaring the contract. Constructors check all class invariants, including static and volatile invariants (see <code class="computeroutput"><a class="link" href="BOOST_CONTRACT_INVARIANT.html" title="Macro BOOST_CONTRACT_INVARIANT">BOOST_CONTRACT_INVARIANT</a></code>,  <code class="computeroutput"><a class="link" href="BOOST_CO_idm45394998621472.html" title="Macro BOOST_CONTRACT_STATIC_INVARIANT">BOOST_CONTRACT_STATIC_INVARIANT</a></code>, and  <code class="computeroutput"><a class="link" href="BOOST_CO_idm45394998635328.html" title="Macro BOOST_CONTRACT_INVARIANT_VOLATILE">BOOST_CONTRACT_INVARIANT_VOLATILE</a></code>). (This is a variadic macro parameter so it can contain commas not protected by round parenthesis.) </p></li>
  81 <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>
  82 </ul></div>
  83 <p>
  84 </p>
  85 <p><span class="bold"><strong>See Also:</strong></span></p>
  86 <p> <a class="link" href="boost_contract/extras.html#boost_contract.extras.disable_contract_compilation__macro_interface_" title="Disable Contract Compilation (Macro Interface)">
  87         Disable Contract Compilation</a>,  <a class="link" href="boost_contract/tutorial.html#boost_contract.tutorial.constructors" title="Constructors"> Constructors</a> </p>
  88 <p>
  89 </p>
  90 <p>
  91 </p>
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  96 <td align="right"><div class="copyright-footer">Copyright &#169; 2008-2019 Lorenzo Caminiti<p>
  97         Distributed under the Boost Software License, Version 1.0 (see accompanying
  98         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>)
  99       </p>
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