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25 <div class="refentry">
26 <a name="BOOST_CONTRACT_DESTRUCTOR"></a><div class="titlepage"></div>
27 <div class="refnamediv">
28 <h2><span class="refentrytitle">Macro BOOST_CONTRACT_DESTRUCTOR</span></h2>
29 <p>BOOST_CONTRACT_DESTRUCTOR — Program contracts that can be completely disabled at compile-time for destructors. </p>
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: <<a class="link" href="reference.html#header.boost.contract_macro_hpp" title="Header <boost/contract_macro.hpp>">boost/contract_macro.hpp</a>>
34 </span>BOOST_CONTRACT_DESTRUCTOR(...)</pre></div>
35 <div class="refsect1">
36 <a name="idm45707992404848"></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 destructors (destructors cannot have preconditions, see <a class="link" href="boost_contract/contract_programming_overview.html#boost_contract.contract_programming_overview.destructor_calls" title="Destructor Calls"> Destructor Calls</a>):</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>
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>
46 <span class="keyword">public</span><span class="special">:</span>
47 <span class="special">~</span><span class="identifier">u</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_DESTRUCTOR</span><span class="special">(</span><span class="keyword">this</span><span class="special">)</span>
50 <span class="comment">// No `PRECONDITION` (destructors have no preconditions).</span>
51 <span class="identifier">BOOST_CONTRACT_OLD</span><span class="special">(</span><span class="special">[</span><span class="special">&</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_expr</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">&</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">&</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>
65 <span class="special">...</span> <span class="comment">// Destructor body.</span>
66 <span class="special">}</span>
68 <span class="special">...</span>
69 <span class="special">}</span><span class="special">;</span>
71 <p>For optimization, this can be omitted for destructors that do not have postconditions and exception guarantees, within classes that have no invariants.</p>
72 <p><code class="computeroutput">BOOST_CONTRACT_DESTRUCTOR(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_idm45394999594544.html" title="Macro BOOST_CONTRACT_NO_DESTRUCTORS">BOOST_CONTRACT_NO_DESTRUCTORS</a></code> is defined):</p>
73 <pre class="programlisting"><span class="preprocessor">#ifndef</span> <span class="identifier">BOOST_CONTRACT_NO_DESTRUCTORS</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">destructor</span><span class="special">(</span><span class="identifier">obj</span><span class="special">)</span>
76 <span class="preprocessor">#endif</span>
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 destructor declaring the contract. Destructors check all class invariants, including static and volatile invariants (see <a class="link" href="boost_contract/tutorial.html#boost_contract.tutorial.class_invariants" title="Class Invariants">
81 Class Invariants</a> and <a class="link" href="boost_contract/extras.html#boost_contract.extras.volatile_public_functions" title="Volatile Public Functions">
82 Volatile Public Functions</a>). (This is a variadic macro parameter so it can contain commas not protected by round parenthesis.) </p></li>
83 <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>
87 <p><span class="bold"><strong>See Also:</strong></span></p>
88 <p> <a class="link" href="boost_contract/extras.html#boost_contract.extras.disable_contract_compilation__macro_interface_" title="Disable Contract Compilation (Macro Interface)">
89 Disable Contract Compilation</a>, <a class="link" href="boost_contract/tutorial.html#boost_contract.tutorial.destructors" title="Destructors"> Destructors</a> </p>
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98 <td align="right"><div class="copyright-footer">Copyright © 2008-2019 Lorenzo Caminiti<p>
99 Distributed under the Boost Software License, Version 1.0 (see accompanying
100 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>)
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