r">old</span><span class="special">(</span><span class="identifier">F</span> <span class="keyword">const</span> <span class="special">&amp;</span> f<span class="special">)</span><span class="special">;</span></pre>Allow to specify old value copies at body. <p>It should often be sufficient to initialize old value pointers as soon as they are declared, without using this function (see  <a class="link" href="../../boost_contract/advanced.html#boost_contract.advanced.old_value_copies_at_body" title="Old Value C