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Updated docs.
[SVN r77899]
This commit is contained in:
@ -41,7 +41,7 @@
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and Platforms</a>
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</h3></div></div></div>
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<p>
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The authors originally developed and tested the library on:
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The authors originally developed and tested this library on:
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</p>
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<div class="orderedlist"><ol class="orderedlist" type="1">
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<li class="listitem">
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@ -56,7 +56,8 @@
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<p>
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See the library <a href="http://www.boost.org/development/tests/release/developer/functional-overloaded_function.html" target="_top">regressions
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test results</a> for detailed information on supported compilers and
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platforms.
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platforms. Check the library regression test <a href="../../../test/Jamfile.v2" target="_top"><code class="literal">Jamfile.v2</code></a>
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for any special configuration that might be required for a specific compiler.
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</p>
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</div>
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<div class="section boost_functional_overloadedfunction_Getting_Started_installation">
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@ -72,9 +73,9 @@
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<p>
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The maximum number of functions to overload is given by the <code class="computeroutput"><a class="link" href="../BOOST_FUNCTIONAL_OVERLOADED_FUNCTION_CONFIG_OVERLOAD_MAX.html" title="Macro BOOST_FUNCTIONAL_OVERLOADED_FUNCTION_CONFIG_OVERLOAD_MAX">BOOST_FUNCTIONAL_OVERLOADED_FUNCTION_CONFIG_OVERLOAD_MAX</a></code>
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configuration macro. The maximum number of function parameters for each of
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the specified function types is given by the <code class="computeroutput"><a class="link" href="../BOOST_FUNCTIONAL_OVERLOADED_FUNCTION_CONFIG_ARITY_MAX.html" title="Macro BOOST_FUNCTIONAL_OVERLOADED_FUNCTION_CONFIG_ARITY_MAX">BOOST_FUNCTIONAL_OVERLOADED_FUNCTION_CONFIG_ARITY_MAX</a></code>
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the specified function type is given by the <code class="computeroutput"><a class="link" href="../BOOST_FUNCTIONAL_OVERLOADED_FUNCTION_CONFIG_ARITY_MAX.html" title="Macro BOOST_FUNCTIONAL_OVERLOADED_FUNCTION_CONFIG_ARITY_MAX">BOOST_FUNCTIONAL_OVERLOADED_FUNCTION_CONFIG_ARITY_MAX</a></code>
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configuration macro. All configuration macros have appropriate default values
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when they are left undefined by the user.
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when they are left undefined.
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</p>
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</div>
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</div>
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|
@ -39,10 +39,20 @@
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<a name="boost_functional_overloadedfunction.Tutorial.overloading"></a><a class="link" href="Tutorial.html#boost_functional_overloadedfunction.Tutorial.overloading" title="Overloading">Overloading</a>
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</h3></div></div></div>
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<p>
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Consider the following functions with distinct signatures:
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Consider the following functions which have distinct signatures:
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</p>
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<p>
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[identity_decls]
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</p>
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<pre class="programlisting"><span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">&</span> <span class="identifier">identity_s</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">&</span> <span class="identifier">x</span><span class="special">)</span> <span class="comment">// Function (as pointer).</span>
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<span class="special">{</span> <span class="keyword">return</span> <span class="identifier">x</span><span class="special">;</span> <span class="special">}</span>
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<span class="keyword">int</span> <span class="identifier">identity_i_impl</span><span class="special">(</span><span class="keyword">int</span> <span class="identifier">x</span><span class="special">)</span> <span class="special">{</span> <span class="keyword">return</span> <span class="identifier">x</span><span class="special">;</span> <span class="special">}</span>
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<span class="keyword">int</span> <span class="special">(&</span><span class="identifier">identity_i</span><span class="special">)(</span><span class="keyword">int</span><span class="special">)</span> <span class="special">=</span> <span class="identifier">identity_i_impl</span><span class="special">;</span> <span class="comment">// Function reference.</span>
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<span class="keyword">double</span> <span class="identifier">identity_d_impl</span><span class="special">(</span><span class="keyword">double</span> <span class="identifier">x</span><span class="special">)</span> <span class="special">{</span> <span class="keyword">return</span> <span class="identifier">x</span><span class="special">;</span> <span class="special">}</span>
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<span class="identifier">boost</span><span class="special">::</span><span class="identifier">function</span><span class="special"><</span><span class="keyword">double</span> <span class="special">(</span><span class="keyword">double</span><span class="special">)></span> <span class="identifier">identity_d</span> <span class="special">=</span> <span class="identifier">identity_d_impl</span><span class="special">;</span> <span class="comment">// Functor.</span>
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</pre>
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<p>
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</p>
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<p>
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This library header <code class="computeroutput"><a class="link" href="../reference.html#header.boost.functional.overloaded_function_hpp" title="Header <boost/functional/overloaded_function.hpp>">boost/functional/overloaded_function.hpp</a></code>
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@ -61,16 +71,15 @@
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<span class="special">></span> <span class="identifier">identity</span><span class="special">(</span><span class="identifier">identity_s</span><span class="special">,</span> <span class="identifier">identity_i</span><span class="special">,</span> <span class="identifier">identity_d</span><span class="special">);</span>
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<span class="comment">// All calls via single `identity` function.</span>
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<span class="identifier">BOOST_CHECK</span><span class="special">(</span><span class="identifier">identity</span><span class="special">(</span><span class="string">"abc"</span><span class="special">)</span> <span class="special">==</span> <span class="string">"abc"</span><span class="special">);</span>
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<span class="identifier">BOOST_CHECK</span><span class="special">(</span><span class="identifier">identity</span><span class="special">(</span><span class="number">123</span><span class="special">)</span> <span class="special">==</span> <span class="number">123</span><span class="special">);</span>
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<span class="identifier">BOOST_CHECK</span><span class="special">(</span><span class="identifier">identity</span><span class="special">(</span><span class="number">1.23</span><span class="special">)</span> <span class="special">==</span> <span class="number">1.23</span><span class="special">);</span>
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<span class="identifier">BOOST_TEST</span><span class="special">(</span><span class="identifier">identity</span><span class="special">(</span><span class="string">"abc"</span><span class="special">)</span> <span class="special">==</span> <span class="string">"abc"</span><span class="special">);</span>
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<span class="identifier">BOOST_TEST</span><span class="special">(</span><span class="identifier">identity</span><span class="special">(</span><span class="number">123</span><span class="special">)</span> <span class="special">==</span> <span class="number">123</span><span class="special">);</span>
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<span class="identifier">BOOST_TEST</span><span class="special">(</span><span class="identifier">identity</span><span class="special">(</span><span class="number">1.23</span><span class="special">)</span> <span class="special">==</span> <span class="number">1.23</span><span class="special">);</span>
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</pre>
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<p>
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</p>
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<p>
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Note how function types in the following format are passed as template parameters
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to <code class="computeroutput"><a class="link" href="../boost/overloaded_function.html" title="Class template overloaded_function">boost::overloaded_function</a></code>
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(this is the format of <a href="http://www.boost.org/libs/function" target="_top">Boost.Function</a>'s
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Note how each function type is passed as a template parameter of <code class="computeroutput"><a class="link" href="../boost/overloaded_function.html" title="Class template overloaded_function">boost::overloaded_function</a></code> using
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the following syntax (this is <a href="http://www.boost.org/libs/function" target="_top">Boost.Function</a>'s
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preferred syntax):
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</p>
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<pre class="programlisting"><span class="emphasis"><em>result-type</em></span> <span class="special">(</span><span class="emphasis"><em>argument1-type</em></span><span class="special">,</span> <span class="emphasis"><em>argument2-type</em></span><span class="special">,</span> <span class="special">...)</span>
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@ -79,10 +88,10 @@
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Then the relative function pointers, function references, or <a href="http://en.wikipedia.org/wiki/Polymorphism_(computer_science)" target="_top">monomorphic
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function</a> objects are passed to the <code class="computeroutput"><a class="link" href="../boost/overloaded_function.html" title="Class template overloaded_function">boost::overloaded_function</a></code>
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constructor matching the order of the specified template parameters. <sup>[<a name="boost_functional_overloadedfunction.Tutorial.overloading.f0" href="#ftn.boost_functional_overloadedfunction.Tutorial.overloading.f0" class="footnote">2</a>]</sup> In the above example, <code class="computeroutput"><span class="identifier">identity_s</span></code>
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is passed as function pointer (the function address is automatically taken
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from the function name by compiler), <code class="computeroutput"><span class="identifier">identity_i</span></code>
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as function reference, and <code class="computeroutput"><span class="identifier">identity_d</span></code>
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as function object.
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is passed as a function pointer (the function address is automatically taken
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from the function name by the compiler), <code class="computeroutput"><span class="identifier">identity_i</span></code>
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as a function reference, and <code class="computeroutput"><span class="identifier">identity_d</span></code>
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as a function object.
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</p>
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<p>
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All specified function types must have distinct parameters from one another
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@ -114,9 +123,9 @@
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<pre class="programlisting"><span class="identifier">BOOST_AUTO</span><span class="special">(</span><span class="identifier">identity</span><span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">make_overloaded_function</span><span class="special">(</span>
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<span class="identifier">identity_s</span><span class="special">,</span> <span class="identifier">identity_i</span><span class="special">,</span> <span class="identifier">identity_d</span><span class="special">));</span>
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<span class="identifier">BOOST_CHECK</span><span class="special">(</span><span class="identifier">identity</span><span class="special">(</span><span class="string">"abc"</span><span class="special">)</span> <span class="special">==</span> <span class="string">"abc"</span><span class="special">);</span>
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<span class="identifier">BOOST_CHECK</span><span class="special">(</span><span class="identifier">identity</span><span class="special">(</span><span class="number">123</span><span class="special">)</span> <span class="special">==</span> <span class="number">123</span><span class="special">);</span>
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<span class="identifier">BOOST_CHECK</span><span class="special">(</span><span class="identifier">identity</span><span class="special">(</span><span class="number">1.23</span><span class="special">)</span> <span class="special">==</span> <span class="number">1.23</span><span class="special">);</span>
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<span class="identifier">BOOST_TEST</span><span class="special">(</span><span class="identifier">identity</span><span class="special">(</span><span class="string">"abc"</span><span class="special">)</span> <span class="special">==</span> <span class="string">"abc"</span><span class="special">);</span>
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<span class="identifier">BOOST_TEST</span><span class="special">(</span><span class="identifier">identity</span><span class="special">(</span><span class="number">123</span><span class="special">)</span> <span class="special">==</span> <span class="number">123</span><span class="special">);</span>
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<span class="identifier">BOOST_TEST</span><span class="special">(</span><span class="identifier">identity</span><span class="special">(</span><span class="number">1.23</span><span class="special">)</span> <span class="special">==</span> <span class="number">1.23</span><span class="special">);</span>
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</pre>
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<p>
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</p>
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@ -135,7 +144,7 @@
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<p>
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Another case where <code class="computeroutput"><a class="link" href="../boost/make_overloaded_function.html" title="Function template make_overloaded_function">boost::make_overloaded_function</a></code>
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can be useful is when the overloaded function object is passed to a function
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template which can hide the specific <code class="computeroutput"><a class="link" href="../boost/overloaded_function.html" title="Class template overloaded_function">boost::overloaded_function</a></code>
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template which can hold the specific <code class="computeroutput"><a class="link" href="../boost/overloaded_function.html" title="Class template overloaded_function">boost::overloaded_function</a></code>
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type using a template parameter. For example (see also <a href="../../../test/make_call.cpp" target="_top"><code class="literal">make_call.cpp</code></a>
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and <a href="../../../test/identity.hpp" target="_top"><code class="literal">identity.hpp</code></a>):
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</p>
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@ -143,9 +152,9 @@
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</p>
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<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> <span class="identifier">F</span><span class="special">></span>
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<span class="keyword">void</span> <span class="identifier">check</span><span class="special">(</span><span class="identifier">F</span> <span class="identifier">identity</span><span class="special">)</span> <span class="special">{</span>
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<span class="identifier">BOOST_CHECK</span><span class="special">(</span><span class="identifier">identity</span><span class="special">(</span><span class="string">"abc"</span><span class="special">)</span> <span class="special">==</span> <span class="string">"abc"</span><span class="special">);</span>
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<span class="identifier">BOOST_CHECK</span><span class="special">(</span><span class="identifier">identity</span><span class="special">(</span><span class="number">123</span><span class="special">)</span> <span class="special">==</span> <span class="number">123</span><span class="special">);</span>
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<span class="identifier">BOOST_CHECK</span><span class="special">(</span><span class="identifier">identity</span><span class="special">(</span><span class="number">1.23</span><span class="special">)</span> <span class="special">==</span> <span class="number">1.23</span><span class="special">);</span>
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<span class="identifier">BOOST_TEST</span><span class="special">(</span><span class="identifier">identity</span><span class="special">(</span><span class="string">"abc"</span><span class="special">)</span> <span class="special">==</span> <span class="string">"abc"</span><span class="special">);</span>
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<span class="identifier">BOOST_TEST</span><span class="special">(</span><span class="identifier">identity</span><span class="special">(</span><span class="number">123</span><span class="special">)</span> <span class="special">==</span> <span class="number">123</span><span class="special">);</span>
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<span class="identifier">BOOST_TEST</span><span class="special">(</span><span class="identifier">identity</span><span class="special">(</span><span class="number">1.23</span><span class="special">)</span> <span class="special">==</span> <span class="number">1.23</span><span class="special">);</span>
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<span class="special">}</span>
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</pre>
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<p>
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@ -154,6 +163,27 @@
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</p>
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<pre class="programlisting"><span class="identifier">check</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">make_overloaded_function</span><span class="special">(</span><span class="identifier">identity_s</span><span class="special">,</span> <span class="identifier">identity_i</span><span class="special">,</span> <span class="identifier">identity_d</span><span class="special">));</span>
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</pre>
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<p>
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</p>
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<p>
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The library implementation of <code class="computeroutput"><a class="link" href="../boost/make_overloaded_function.html" title="Function template make_overloaded_function">boost::make_overloaded_function</a></code>
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uses <a href="http://www.boost.org/doc/libs/typeof" target="_top">Boost.Typeof</a>
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to automatically deduce some of the function types. In order to compile code
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in <a href="http://www.boost.org/doc/libs/typeof" target="_top">Boost.Typeof</a>
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emulation mode, all types should be properly registered using <code class="computeroutput"><span class="identifier">BOOST_TYPEOF_REGISTER_TYPE</span></code> and <code class="computeroutput"><span class="identifier">BOOST_TYPEOF_REGISTER_TEMPLATE</span></code>, or appropriate
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<a href="http://www.boost.org/doc/libs/typeof" target="_top">Boost.Typeof</a> headers
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should be included (see <a href="http://www.boost.org/doc/libs/typeof" target="_top">Boost.Typeof</a>
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for more information). For the above examples, it is sufficient to include
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the <a href="http://www.boost.org/doc/libs/typeof" target="_top">Boost.Typeof</a>
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header that registers <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span></code>
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(this library does not require to register <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">function</span></code>
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for <a href="http://www.boost.org/doc/libs/typeof" target="_top">Boost.Typeof</a>
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emulation):
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</p>
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<p>
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</p>
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<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">typeof</span><span class="special">/</span><span class="identifier">std</span><span class="special">/</span><span class="identifier">string</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> <span class="comment">// No need to register `boost::function`.</span>
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</pre>
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<p>
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</p>
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</div>
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@ -171,6 +201,8 @@
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pointers and function references). Finally, monomorphic function objects
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are instances of classes with a non-template call operator of the form
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<code class="literal"><span class="emphasis"><em>result-type </em></span></code><code class="computeroutput"><span class="keyword">operator</span><span class="special">()(</span></code><code class="literal"><span class="emphasis"><em>argument1-type</em></span></code><code class="computeroutput"><span class="special">,</span> <span class="special">...)</span></code>.
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Unfortunately, it is not possible to support polymorphic function objects
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(see <a href="http://lists.boost.org/Archives/boost/2012/03/191744.php" target="_top">http://lists.boost.org/Archives/boost/2012/03/191744.php</a>).
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</p></div>
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<div class="footnote"><p><sup>[<a id="ftn.boost_functional_overloadedfunction.Tutorial.overloading.f1" href="#boost_functional_overloadedfunction.Tutorial.overloading.f1" class="para">3</a>] </sup>
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Note that in C++ the function result type is not used for overload resolution
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