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  28 <h2><span class="refentrytitle">Function make_old</span></h2>
  29 <p>boost::contract::make_old &#8212; Make an old value pointer (for virtual public functions and public functions overrides). </p>
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  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.old_hpp" title="Header &lt;boost/contract/old.hpp&gt;">boost/contract/old.hpp</a>&gt;
  33
  34 </span>
  35 <a class="link" href="old_pointer.html" title="Class old_pointer">old_pointer</a> <span class="identifier">make_old</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> <a class="link" href="old_value.html" title="Class old_value">old_value</a> <span class="keyword">const</span> <span class="special">&amp;</span> old<span class="special">)</span><span class="special">;</span></pre></div>
  36 <div class="refsect1">
  37 <a name="idm45707994166688"></a><h2>Description</h2>
  38 <p>The related old value pointer will not be null if the specified old value was actually copied. This function is usually only called by code expanded by <code class="computeroutput">BOOST_CONTRACT_OLDOF(v, old_expr)</code> as in:</p>
  39 <pre class="programlisting"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">contract</span><span class="special">::</span><span class="identifier">make_old</span><span class="special">(</span><span class="identifier">v</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">copy_old</span><span class="special">(</span><span class="identifier">v</span><span class="special">)</span> <span class="special">?</span> <span class="identifier">old_expr</span> <span class="special">:</span>
  40         <span class="identifier">boost</span><span class="special">::</span><span class="identifier">contract</span><span class="special">::</span><span class="identifier">null_old</span><span class="special">(</span><span class="special">)</span><span class="special">)</span>
  41 </pre>
  42 <p><span class="bold"><strong>See Also:</strong></span></p>
  43 <p> <a class="link" href="../../boost_contract/extras.html#boost_contract.extras.no_macros__and_no_variadic_macros_" title="No Macros (and No Variadic Macros)"> No Macros</a></p>
  44 <p>
  45 </p>
  46 <p>
  47
  48
  49 </p>
  50 <div class="variablelist"><table border="0" class="variablelist compact">
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  53 <col>
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  57 <td><p><span class="term">Parameters:</span></p></td>
  58 <td><div class="variablelist"><table border="0" class="variablelist compact">
  59 <colgroup>
  60 <col align="left" valign="top">
  61 <col>
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  65 <td><p><span class="term"><code class="computeroutput">old</code></span></p></td>
  66 <td><p>Old value which is usually implicitly constructed from the user old value expression to be copied (use the ternary operator <code class="computeroutput">?:</code> to completely avoid to evaluate the old value expression when <code class="computeroutput">boost::contract::copy_old(v)</code> is <code class="computeroutput">false</code>).</p></td>
  67 </tr>
  68 <tr>
  69 <td><p><span class="term"><code class="computeroutput">v</code></span></p></td>
  70 <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 or overriding public function declaring the contract. </p></td>
  71 </tr>
  72 </tbody>
  73 </table></div></td>
  74 </tr>
  75 <tr>
  76 <td><p><span class="term">Returns:</span></p></td>
  77 <td><p>Old value pointer (usually implicitly converted to either  <code class="computeroutput"><a class="link" href="old_ptr.html" title="Class template old_ptr">boost::contract::old_ptr</a></code> or  <code class="computeroutput"><a class="link" href="old_ptr_if_copyable.html" title="Class template old_ptr_if_copyable">boost::contract::old_ptr_if_copyable</a></code> in user code). </p></td>
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