ecial">;</span></pre>Construct this object by making one single copy of the specified old value. <p>This is the only operation within this library that actually copies old values. This ensures this library makes one and only one copy of an old value (if they actually need to be copied, see <code class="computeroutput"><code class="computeroutput"><a class="link" href="../../BOOST_CONTRACT_NO_OLDS.html" title="Macro BOOST_CONTRACT_NO_OLDS">BOOST_CONTRACT_NO_OLDS</a></code></code>).</p>
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