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  26 <a name="boost.contract.call_if__idm45123870948032"></a><div class="titlepage"></div>
  27 <div class="refnamediv">
  28 <h2><span class="refentrytitle">Struct template call_if_statement&lt;false, Then, internal_type&gt;</span></h2>
  29 <p>boost::contract::call_if_statement&lt;false, Then, internal_type&gt; &#8212; Template specialization to handle static predicates that are <code class="computeroutput">false</code>. </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.call_if_hpp" title="Header &lt;boost/contract/call_if.hpp&gt;">boost/contract/call_if.hpp</a>&gt;
  33
  34 </span><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> Then<span class="special">&gt;</span>
  35 <span class="keyword">struct</span> <a class="link" href="call_if__idm45123870948032.html" title="Struct template call_if_statement&lt;false, Then, internal_type&gt;">call_if_statement</a><span class="special">&lt;</span><span class="keyword">false</span><span class="special">,</span> <span class="identifier">Then</span><span class="special">,</span> <span class="identifier">internal_type</span><span class="special">&gt;</span> <span class="special">{</span>
  36   <span class="comment">// <a class="link" href="call_if__idm45123870948032.html#boost.contract.call_if__idm45123870948032construct-copy-destruct">construct/copy/destruct</a></span>
  37   <span class="keyword">explicit</span> <a class="link" href="call_if__idm45123870948032.html#idm45123870913056-bb"><span class="identifier">call_if_statement</span></a><span class="special">(</span><span class="identifier">Then</span> <span class="keyword">const</span> <span class="special">&amp;</span><span class="special">)</span><span class="special">;</span>
  38
  39   <span class="comment">// <a class="link" href="call_if__idm45123870948032.html#idm45123870939664-bb">public member functions</a></span>
  40   <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> Else<span class="special">&gt;</span> <span class="identifier">result_of</span><span class="special">&lt;</span> <span class="identifier">Else</span><span class="special">(</span><span class="special">)</span><span class="special">&gt;</span><span class="special">::</span><span class="identifier">type</span> <a class="link" href="call_if__idm45123870948032.html#idm45123870939104-bb"><span class="identifier">else_</span></a><span class="special">(</span><span class="identifier">Else</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
  41   <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">bool</span> ElseIfPred<span class="special">,</span> <span class="keyword">typename</span> ElseIfThen<span class="special">&gt;</span>
  42     <a class="link" href="call_if_statement.html" title="Struct template call_if_statement">call_if_statement</a><span class="special">&lt;</span> <span class="identifier">ElseIfPred</span><span class="special">,</span> <span class="identifier">ElseIfThen</span> <span class="special">&gt;</span> <a class="link" href="call_if__idm45123870948032.html#idm45123870930448-bb"><span class="identifier">else_if_c</span></a><span class="special">(</span><span class="identifier">ElseIfThen</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
  43   <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> ElseIfPred<span class="special">,</span> <span class="keyword">typename</span> ElseIfThen<span class="special">&gt;</span>
  44     <a class="link" href="call_if_statement.html" title="Struct template call_if_statement">call_if_statement</a><span class="special">&lt;</span> <span class="identifier">ElseIfPred</span><span class="special">::</span><span class="identifier">value</span><span class="special">,</span> <span class="identifier">ElseIfThen</span> <span class="special">&gt;</span>
  45     <a class="link" href="call_if__idm45123870948032.html#idm45123870921696-bb"><span class="identifier">else_if</span></a><span class="special">(</span><span class="identifier">ElseIfThen</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
  46 <span class="special">}</span><span class="special">;</span></pre></div>
  47 <div class="refsect1">
  48 <a name="idm45751731622032"></a><h2>Description</h2>
  49 <p>This template specialization handles all else-branch functor template calls (whether they return void or not). Usually this class template is instantiated only via the return value of  <code class="computeroutput"><a class="link" href="call_if.html" title="Function template call_if">boost::contract::call_if</a></code> and <code class="computeroutput"><a class="link" href="call_if_c.html" title="Function template call_if_c">boost::contract::call_if_c</a></code>.</p>
  50 <p><span class="bold"><strong>See Also:</strong></span></p>
  51 <p> <a class="link" href="../../boost_contract/extras.html#boost_contract.extras.assertion_requirements__templates_" title="Assertion Requirements (Templates)">
  52         Assertion Requirements</a></p>
  53 <p>
  54 </p>
  55 <p>
  56
  57 </p>
  58 <div class="refsect2">
  59 <a name="idm45751731616544"></a><h3>Template Parameters</h3>
  60 <div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
  61 <pre class="literallayout"><span class="keyword">typename</span> Then</pre>
  62 <p>Type of functor template to call when the static predicate is <code class="computeroutput">true</code> (never the case for this template specialization). </p>
  63 </li></ol></div>
  64 </div>
  65 <div class="refsect2">
  66 <a name="idm45751731612672"></a><h3>
  67 <a name="boost.contract.call_if__idm45123870948032construct-copy-destruct"></a><code class="computeroutput">call_if_statement</code>
  68         public
  69        construct/copy/destruct</h3>
  70 <div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
  71 <pre class="literallayout"><span class="keyword">explicit</span> <a name="idm45123870913056-bb"></a><span class="identifier">call_if_statement</span><span class="special">(</span><span class="identifier">Then</span> <span class="keyword">const</span> <span class="special">&amp;</span> f<span class="special">)</span><span class="special">;</span></pre>Construct this object with the then-branch functor template. <p>
  72 </p>
  73 <div class="variablelist"><table border="0" class="variablelist compact">
  74 <colgroup>
  75 <col align="left" valign="top">
  76 <col>
  77 </colgroup>
  78 <tbody><tr>
  79 <td><p><span class="term">Parameters:</span></p></td>
  80 <td><div class="variablelist"><table border="0" class="variablelist compact">
  81 <colgroup>
  82 <col align="left" valign="top">
  83 <col>
  84 </colgroup>
  85 <tbody><tr>
  86 <td><p><span class="term"><code class="computeroutput">f</code></span></p></td>
  87 <td><p>Then-branch nullary functor template. The functor template call <code class="computeroutput">f()</code> is never compiled and executed for this template specialization (because the if-statement static predicate is <code class="computeroutput">false</code>). The return type of <code class="computeroutput">f()</code> must be the same as (or implicitly convertible to) the return type of all other functor template calls specified for this call-if object. </p></td>
  88 </tr></tbody>
  89 </table></div></td>
  90 </tr></tbody>
  91 </table></div>
  92 </li></ol></div>
  93 </div>
  94 <div class="refsect2">
  95 <a name="idm45751731598176"></a><h3>
  96 <a name="idm45123870939664-bb"></a><code class="computeroutput">call_if_statement</code> public member functions</h3>
  97 <div class="orderedlist"><ol class="orderedlist" type="1">
  98 <li class="listitem">
  99 <pre class="literallayout"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> Else<span class="special">&gt;</span> <span class="identifier">result_of</span><span class="special">&lt;</span> <span class="identifier">Else</span><span class="special">(</span><span class="special">)</span><span class="special">&gt;</span><span class="special">::</span><span class="identifier">type</span> <a name="idm45123870939104-bb"></a><span class="identifier">else_</span><span class="special">(</span><span class="identifier">Else</span> f<span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>Specify the else-branch functor template. <div class="note"><table border="0" summary="Note">
 100 <tr>
 101 <td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../../../doc/src/images/note.png"></td>
 102 <th align="left">Note</th>
 103 </tr>
 104 <tr><td align="left" valign="top"><p>The <code class="computeroutput">result_of&lt;Else()&gt;::type</code> expression should be evaluated only when the static predicate is already checked to be <code class="computeroutput">false</code> (because <code class="computeroutput">Else()</code> is required to compile only in that case). Thus, this result-of expression is evaluated lazily only in instantiations of this template specialization.</p></td></tr>
 105 </table></div>
 106 <p>
 107
 108
 109 </p>
 110 <div class="variablelist"><table border="0" class="variablelist compact">
 111 <colgroup>
 112 <col align="left" valign="top">
 113 <col>
 114 </colgroup>
 115 <tbody>
 116 <tr>
 117 <td><p><span class="term">Parameters:</span></p></td>
 118 <td><div class="variablelist"><table border="0" class="variablelist compact">
 119 <colgroup>
 120 <col align="left" valign="top">
 121 <col>
 122 </colgroup>
 123 <tbody><tr>
 124 <td><p><span class="term"><code class="computeroutput">f</code></span></p></td>
 125 <td><p>Else-branch nullary functor template. The functor template call <code class="computeroutput">f()</code> is actually compiled and executed for this template specialization (because the if-statement static predicate is <code class="computeroutput">false</code>). The return type of <code class="computeroutput">f()</code> must be the same as (or implicitly convertible to) the return type of all other functor template calls specified for this call-if object.</p></td>
 126 </tr></tbody>
 127 </table></div></td>
 128 </tr>
 129 <tr>
 130 <td><p><span class="term">Returns:</span></p></td>
 131 <td><p>A copy of the value returned by the call to the else-branch functor template <code class="computeroutput">f()</code>. </p></td>
 132 </tr>
 133 </tbody>
 134 </table></div>
 135 </li>
 136 <li class="listitem">
 137 <pre class="literallayout"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">bool</span> ElseIfPred<span class="special">,</span> <span class="keyword">typename</span> ElseIfThen<span class="special">&gt;</span>
 138   <a class="link" href="call_if_statement.html" title="Struct template call_if_statement">call_if_statement</a><span class="special">&lt;</span> <span class="identifier">ElseIfPred</span><span class="special">,</span> <span class="identifier">ElseIfThen</span> <span class="special">&gt;</span> <a name="idm45123870930448-bb"></a><span class="identifier">else_if_c</span><span class="special">(</span><span class="identifier">ElseIfThen</span> f<span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>Specify an else-if-branch functor template (using a static boolean predicate). <p>
 139
 140
 141 </p>
 142 <div class="variablelist"><table border="0" class="variablelist compact">
 143 <colgroup>
 144 <col align="left" valign="top">
 145 <col>
 146 </colgroup>
 147 <tbody>
 148 <tr>
 149 <td><p><span class="term">Parameters:</span></p></td>
 150 <td><div class="variablelist"><table border="0" class="variablelist compact">
 151 <colgroup>
 152 <col align="left" valign="top">
 153 <col>
 154 </colgroup>
 155 <tbody><tr>
 156 <td><p><span class="term"><code class="computeroutput">f</code></span></p></td>
 157 <td><p>Else-if-branch nullary functor template. The functor template call <code class="computeroutput">f()</code> is actually compiled and executed if and only if <code class="computeroutput">ElseIfPred</code> is <code class="computeroutput">true</code> (because the if-statement static predicate is already <code class="computeroutput">false</code> for this template specialization). The return type of <code class="computeroutput">f()</code> must be the same as (or implicitly convertible to) the return type of all other functor template calls specified for this call-if object.</p></td>
 158 </tr></tbody>
 159 </table></div></td>
 160 </tr>
 161 <tr>
 162 <td><p><span class="term">Template Parameters:</span></p></td>
 163 <td><div class="variablelist"><table border="0" class="variablelist compact">
 164 <colgroup>
 165 <col align="left" valign="top">
 166 <col>
 167 </colgroup>
 168 <tbody><tr>
 169 <td><p><span class="term"><code class="computeroutput">ElseIfPred</code></span></p></td>
 170 <td><p>Static boolean predicate selecting which functor template call to compile and execute.</p></td>
 171 </tr></tbody>
 172 </table></div></td>
 173 </tr>
 174 <tr>
 175 <td><p><span class="term">Returns:</span></p></td>
 176 <td><p>A call-if statement so the else statement and additional else-if statements can be specified if needed. Eventually, this will be the return value of the functor template call being compiled and executed. </p></td>
 177 </tr>
 178 </tbody>
 179 </table></div>
 180 </li>
 181 <li class="listitem">
 182 <pre class="literallayout"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> ElseIfPred<span class="special">,</span> <span class="keyword">typename</span> ElseIfThen<span class="special">&gt;</span>
 183   <a class="link" href="call_if_statement.html" title="Struct template call_if_statement">call_if_statement</a><span class="special">&lt;</span> <span class="identifier">ElseIfPred</span><span class="special">::</span><span class="identifier">value</span><span class="special">,</span> <span class="identifier">ElseIfThen</span> <span class="special">&gt;</span>
 184   <a name="idm45123870921696-bb"></a><span class="identifier">else_if</span><span class="special">(</span><span class="identifier">ElseIfThen</span> f<span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>Specify an else-if-branch functor template (using a nullary boolen meta-function). <p>
 185
 186
 187 </p>
 188 <div class="variablelist"><table border="0" class="variablelist compact">
 189 <colgroup>
 190 <col align="left" valign="top">
 191 <col>
 192 </colgroup>
 193 <tbody>
 194 <tr>
 195 <td><p><span class="term">Parameters:</span></p></td>
 196 <td><div class="variablelist"><table border="0" class="variablelist compact">
 197 <colgroup>
 198 <col align="left" valign="top">
 199 <col>
 200 </colgroup>
 201 <tbody><tr>
 202 <td><p><span class="term"><code class="computeroutput">f</code></span></p></td>
 203 <td><p>Else-if-branch nullary functor template. The functor template call <code class="computeroutput">f()</code> is actually compiled and executed if and only if <code class="computeroutput">ElseIfPred::value</code> is <code class="computeroutput">true</code> (because the if-statement static predicate is already <code class="computeroutput">false</code> for this template specialization). The return type of <code class="computeroutput">f()</code> must be the same as (or implicitly convertible to) the return type of all other functor template calls specified for this call-if object.</p></td>
 204 </tr></tbody>
 205 </table></div></td>
 206 </tr>
 207 <tr>
 208 <td><p><span class="term">Template Parameters:</span></p></td>
 209 <td><div class="variablelist"><table border="0" class="variablelist compact">
 210 <colgroup>
 211 <col align="left" valign="top">
 212 <col>
 213 </colgroup>
 214 <tbody><tr>
 215 <td><p><span class="term"><code class="computeroutput">ElseIfPred</code></span></p></td>
 216 <td><p>Nullary boolean meta-function selecting which functor template call to compile and execute.</p></td>
 217 </tr></tbody>
 218 </table></div></td>
 219 </tr>
 220 <tr>
 221 <td><p><span class="term">Returns:</span></p></td>
 222 <td><p>A call-if statement so the else statement and additional else-if statements can be specified if needed. Eventually, this will be the return value of the functor template call being compiled and executed. </p></td>
 223 </tr>
 224 </tbody>
 225 </table></div>
 226 </li>
 227 </ol></div>
 228 </div>
 229 </div>
 230 </div>
 231 <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
 232 <td align="left"></td>
 233 <td align="right"><div class="copyright-footer">Copyright &#169; 2008-2018 Lorenzo Caminiti<p>
 234         Distributed under the Boost Software License, Version 1.0 (see accompanying
 235         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>)
 236       </p>
 237 </div></td>
 238 </tr></table>
 239 <hr>
 240 <div class="spirit-nav">
 241 <a accesskey="p" href="call_if_statement.html"><img src="../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../../reference.html#header.boost.contract.call_if_hpp"><img src="../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../index.html"><img src="../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="call_if__idm45123870909024.html"><img src="../../../../../../doc/src/images/next.png" alt="Next"></a>
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