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<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> <title>Class template function</title> <link rel="stylesheet" href="../../../doc/src/boostbook.css" type="text/css"> <meta name="generator" content="DocBook XSL Stylesheets V1.78.1"> <link rel="home" href="../index.html" title="The Boost C++ Libraries BoostBook Documentation Subset"> <link rel="up" href="../function/reference.html#header.boost.function_hpp" title="Header <boost/function.hpp>"> <link rel="prev" href="functionN/sig.html" title="Struct template sig"> <link rel="next" href="function/sig.html" title="Struct template sig"> </head> <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> <table cellpadding="2" width="100%"><tr> <td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../boost.png"></td> <td align="center"><a href="../../../index.html">Home</a></td> <td align="center"><a href="../../../libs/libraries.htm">Libraries</a></td> <td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> <td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> <td align="center"><a href="../../../more/index.htm">More</a></td> </tr></table> <hr> <div class="spirit-nav"> <a accesskey="p" href="functionN/sig.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../function/reference.html#header.boost.function_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="function/sig.html"><img src="../../../doc/src/images/next.png" alt="Next"></a> </div> <div class="refentry"> <a name="boost.function"></a><div class="titlepage"></div> <div class="refnamediv"> <h2>Class template function</h2> boost::function — A generalized function pointer that can be used for callbacks or wrapping function objects. </div> <h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2> <div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis">// In header: <<a class="link" href="../function/reference.html#header.boost.function_hpp" title="Header <boost/function.hpp>">boost/function.hpp</a>> template<typename Signature> class <a class="link" href="function.html" title="Class template function">function</a> : public <a class="link" href="functionN.html" title="Class template functionN">functionN</a><R, T1, T2, ..., TN> { public: // types typedef R <a name="boost.function.result_type"></a>result_type; typedef T1 <a name="boost.function.argument_type"></a>argument_type; // If N == 1 typedef T1 <a name="boost.function.first_argument_type"></a>first_argument_type; // If N == 2 typedef T2 <a name="boost.function.second_argument_type"></a>second_argument_type; // If N == 2 typedef T1 <a name="boost.function.arg1_type"></a>arg1_type; typedef T2 <a name="boost.function.arg2_type"></a>arg2_type; . . . typedef TN <a name="boost.function.argN_type"></a>argN_type; // static constants static const int arity = N; // member classes/structs/unions // <a class="link" href="../lambda.html" title="Chapter 16. Boost.Lambda">Lambda</a> library support template<typename Args> struct <a class="link" href="function/sig.html" title="Struct template sig">sig</a> { // types typedef result_type <a class="link" href="function/sig.html#boost.function.sig.type">type</a>; }; // <a class="link" href="function.html#boost.functionconstruct-copy-destruct">construct/copy/destruct</a> <a class="link" href="function.html#idp75737696-bb">function</a>(); <a class="link" href="function.html#idp39655760-bb">function</a>(const <a class="link" href="functionN.html" title="Class template functionN">functionN</a>&); <a class="link" href="function.html#idp106826448-bb">function</a>(<a class="link" href="functionN.html" title="Class template functionN">functionN</a>&&); <a class="link" href="function.html#idp110867712-bb">function</a>(const <a class="link" href="function.html" title="Class template function">function</a>&); <a class="link" href="function.html#idp42720176-bb">function</a>(<a class="link" href="function.html" title="Class template function">function</a>&&); template<typename F> <a class="link" href="function.html#idp40296688-bb">function</a>(F); template<typename F, typename Allocator> <a class="link" href="function.html#idp40994480-bb">function</a>(F, Allocator); function& <a class="link" href="function.html#idp69909120-bb">operator=</a>(const <a class="link" href="functionN.html" title="Class template functionN">functionN</a>&); function& <a class="link" href="function.html#idp37708288-bb">operator=</a>(<a class="link" href="functionN.html" title="Class template functionN">functionN</a>&&); function& <a class="link" href="function.html#idp38571792-bb">operator=</a>(const <a class="link" href="function.html" title="Class template function">function</a>&); function& <a class="link" href="function.html#idp105085072-bb">operator=</a>(<a class="link" href="function.html" title="Class template function">function</a>&&); <a class="link" href="function.html#idp45860512-bb">~function</a>(); // <a class="link" href="function.html#idp108302096-bb">modifiers</a> void <a class="link" href="function.html#idp108302656-bb">swap</a>(const <a class="link" href="function.html" title="Class template function">function</a>&); void <a class="link" href="function.html#idp72870112-bb">clear</a>(); // <a class="link" href="function.html#idp99731696-bb">capacity</a> bool <a class="link" href="function.html#idp39557232-bb">empty</a>() const; <a class="link" href="function.html#idp41154480-bb">operator safe_bool</a>() const; bool <a class="link" href="function.html#idp76193136-bb">operator!</a>() const; // <a class="link" href="function.html#idp69032368-bb">target access</a> template<typename Functor> Functor* <a class="link" href="function.html#idp113597808-bb">target</a>(); template<typename Functor> const Functor* <a class="link" href="function.html#idp37917680-bb">target</a>() const; template<typename Functor> bool <a class="link" href="function.html#idp44257488-bb">contains</a>(const Functor&) const; const std::type_info& <a class="link" href="function.html#idp46276608-bb">target_type</a>() const; // <a class="link" href="function.html#idp55139648-bb">invocation</a> result_type <a class="link" href="function.html#idp55140176-bb">operator()</a>(arg1_type, arg2_type, ..., argN_type) const; }; // <a class="link" href="function.html#idp111166064-bb">specialized algorithms</a> template<typename Signature> void <a class="link" href="function.html#boost.function.swap_idp76190448">swap</a>(<a class="link" href="function.html" title="Class template function">function</a><Signature>&, <a class="link" href="function.html" title="Class template function">function</a><Signature>&); // <a class="link" href="function.html#idp48579440-bb">comparison operators</a> template<typename Signature, typename Functor> bool <a class="link" href="function.html#idp113383552-bb">operator==</a>(const <a class="link" href="function.html" title="Class template function">function</a><Signature>&, Functor); template<typename Signature, typename Functor> bool <a class="link" href="function.html#idp95785712-bb">operator==</a>(Functor, const <a class="link" href="function.html" title="Class template function">function</a><Signature>&); template<typename Signature, typename Functor> bool <a class="link" href="function.html#idp37641488-bb">operator==</a>(const <a class="link" href="function.html" title="Class template function">function</a><Signature>&, reference_wrapper<Functor>); template<typename Signature, typename Functor> bool <a class="link" href="function.html#idp105237024-bb">operator==</a>(reference_wrapper<Functor>, const <a class="link" href="function.html" title="Class template function">function</a><Signature>&); template<typename Signature1, typename Signature2> void <a class="link" href="function.html#idp69032896-bb">operator==</a>(const <a class="link" href="function.html" title="Class template function">function</a><Signature1>&, const <a class="link" href="function.html" title="Class template function">function</a><Signature2>&); template<typename Signature, typename Functor> bool <a class="link" href="function.html#idp47556672-bb">operator!=</a>(const <a class="link" href="function.html" title="Class template function">function</a><Signature>&, Functor); template<typename Signature, typename Functor> bool <a class="link" href="function.html#idp101036032-bb">operator!=</a>(Functor, const <a class="link" href="function.html" title="Class template function">function</a><Signature>&); template<typename Signature, typename Functor> bool <a class="link" href="function.html#idp54996816-bb">operator!=</a>(const <a class="link" href="function.html" title="Class template function">function</a><Signature>&, reference_wrapper<Functor>); template<typename Signature, typename Functor> bool <a class="link" href="function.html#idp110874944-bb">operator!=</a>(reference_wrapper<Functor>, const <a class="link" href="function.html" title="Class template function">function</a><Signature>&); template<typename Signature1, typename Signature2> void <a class="link" href="function.html#idp99861584-bb">operator!=</a>(const <a class="link" href="function.html" title="Class template function">function</a><Signature1>&, const <a class="link" href="function.html" title="Class template function">function</a><Signature2>&);</pre></div> <div class="refsect1"> <a name="idp210007408"></a><h2>Description</h2> Class template <a class="link" href="function.html" title="Class template function">function</a> is a thin wrapper around the numbered class templates <a class="link" href="functionN.html" title="Class template functionN">function0</a>, <a class="link" href="functionN.html" title="Class template functionN">function1</a>, etc. It accepts a function type with N arguments and will will derive from <a class="link" href="functionN.html" title="Class template functionN">functionN</a> instantiated with the arguments it receives. The semantics of all operations in class template <a class="link" href="function.html" title="Class template function">function</a> are equivalent to that of the underlying <a class="link" href="functionN.html" title="Class template functionN">functionN</a> object, although additional member functions are required to allow proper copy construction and copy assignment of function objects. <div class="refsect2"> <a name="idp210014112"></a><h3>Template Parameters</h3> <div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"> <pre class="literallayout">typename Signature</pre> </li></ol></div> </div> <div class="refsect2"> <a name="idp210016976"></a><h3> <a name="boost.functionconstruct-copy-destruct"></a><code class="computeroutput">function</code> public construct/copy/destruct</h3> <div class="orderedlist"><ol class="orderedlist" type="1"> <li class="listitem"> <pre class="literallayout"><a name="idp75737696-bb"></a>function();</pre> <div class="variablelist"><table border="0" class="variablelist compact"> <colgroup> <col align="left" valign="top"> <col> </colgroup> <tbody> <tr> <td>Postconditions:</td> <td><code class="computeroutput">this-><a class="link" href="function.html#idp39557232-bb">empty</a>()</code></td> </tr> <tr> <td>Throws:</td> <td>Will not throw.</td> </tr> </tbody> </table></div> </li> <li class="listitem"> <pre class="literallayout"><a name="idp39655760-bb"></a>function(const <a class="link" href="functionN.html" title="Class template functionN">functionN</a>& f);</pre> <div class="variablelist"><table border="0" class="variablelist compact"> <colgroup> <col align="left" valign="top"> <col> </colgroup> <tbody> <tr> <td>Postconditions:</td> <td>Contains a copy of the <code class="computeroutput">f</code>'s target, if it has one, or is empty if <code class="computeroutput">f.<a class="link" href="function.html#idp39557232-bb">empty</a>()</code>.</td> </tr> <tr> <td>Throws:</td> <td>Will not throw unless copying the target of <code class="computeroutput">f</code> throws.</td> </tr> </tbody> </table></div> </li> <li class="listitem"> <pre class="literallayout"><a name="idp106826448-bb"></a>function(<a class="link" href="functionN.html" title="Class template functionN">functionN</a>&& f);</pre> <div class="variablelist"><table border="0" class="variablelist compact"> <colgroup> <col align="left" valign="top"> <col> </colgroup> <tbody> <tr> <td>Requires:</td> <td>C++11 compatible compiler.</td> </tr> <tr> <td>Postconditions:</td> <td>Moves the value from <code class="computeroutput">f</code> to <code class="computeroutput">*this</code>. If the argument has its function object allocated on the heap, its buffer will be assigned to <code class="computeroutput">*this</code> leaving argument empty.</td> </tr> <tr> <td>Throws:</td> <td>Will not throw unless argument has its function object allocated not on the heap and copying the target of <code class="computeroutput">f</code> throws.</td> </tr> </tbody> </table></div> </li> <li class="listitem"> <pre class="literallayout"><a name="idp110867712-bb"></a>function(const <a class="link" href="function.html" title="Class template function">function</a>& f);</pre> <div class="variablelist"><table border="0" class="variablelist compact"> <colgroup> <col align="left" valign="top"> <col> </colgroup> <tbody> <tr> <td>Postconditions:</td> <td>Contains a copy of the <code class="computeroutput">f</code>'s target, if it has one, or is empty if <code class="computeroutput">f.<a class="link" href="function.html#idp39557232-bb">empty</a>()</code>.</td> </tr> <tr> <td>Throws:</td> <td>Will not throw unless copying the target of <code class="computeroutput">f</code> throws.</td> </tr> </tbody> </table></div> </li> <li class="listitem"> <pre class="literallayout"><a name="idp42720176-bb"></a>function(<a class="link" href="function.html" title="Class template function">function</a>&& f);</pre> <div class="variablelist"><table border="0" class="variablelist compact"> <colgroup> <col align="left" valign="top"> <col> </colgroup> <tbody> <tr> <td>Requires:</td> <td>C++11 compatible compiler.</td> </tr> <tr> <td>Postconditions:</td> <td>Moves the value from <code class="computeroutput">f</code> to <code class="computeroutput">*this</code>. If the argument has its function object allocated on the heap, its buffer will be assigned to <code class="computeroutput">*this</code> leaving argument empty.</td> </tr> <tr> <td>Throws:</td> <td>Will not throw unless argument has its function object allocated not on the heap and copying the target of <code class="computeroutput">f</code> throws.</td> </tr> </tbody> </table></div> </li> <li class="listitem"> <pre class="literallayout">template<typename F> <a name="idp40296688-bb"></a>function(F f);</pre> <div class="variablelist"><table border="0" class="variablelist compact"> <colgroup> <col align="left" valign="top"> <col> </colgroup> <tbody> <tr> <td>Requires:</td> <td>F is a function object Callable from <code class="computeroutput">this</code>.</td> </tr> <tr> <td>Postconditions:</td> <td> <code class="computeroutput">*this</code> targets a copy of <code class="computeroutput">f</code> if <code class="computeroutput">f</code> is nonempty, or <code class="computeroutput">this-><a class="link" href="function.html#idp39557232-bb">empty</a>()</code> if <code class="computeroutput">f</code> is empty.</td> </tr> </tbody> </table></div> </li> <li class="listitem"> <pre class="literallayout">template<typename F, typename Allocator> <a name="idp40994480-bb"></a>function(F f, Allocator alloc);</pre> <div class="variablelist"><table border="0" class="variablelist compact"> <colgroup> <col align="left" valign="top"> <col> </colgroup> <tbody> <tr> <td>Requires:</td> <td>F is a function object Callable from <code class="computeroutput">this</code>, Allocator is an allocator. The copy constructor and destructor of Allocator shall not throw.</td> </tr> <tr> <td>Postconditions:</td> <td> <code class="computeroutput">*this</code> targets a copy of <code class="computeroutput">f</code> if <code class="computeroutput">f</code> is nonempty, or <code class="computeroutput">this-><a class="link" href="function.html#idp39557232-bb">empty</a>()</code> if <code class="computeroutput">f</code> is empty.</td> </tr> <tr> <td>Effects:</td> <td>If memory allocation is required, the given allocator (or a copy of it) will be used to allocate that memory.</td> </tr> </tbody> </table></div> </li> <li class="listitem"> <pre class="literallayout">function& <a name="idp69909120-bb"></a>operator=(const <a class="link" href="functionN.html" title="Class template functionN">functionN</a>& f);</pre> <div class="variablelist"><table border="0" class="variablelist compact"> <colgroup> <col align="left" valign="top"> <col> </colgroup> <tbody><tr> <td>Postconditions:</td> <td>If copy construction does not throw, <code class="computeroutput">*this</code> targets a copy of <code class="computeroutput">f</code>'s target, if it has one, or is empty if <code class="computeroutput">f.<a class="link" href="function.html#idp39557232-bb">empty</a>()</code>. If copy construction does throw, <code class="computeroutput">this-><a class="link" href="function.html#idp39557232-bb">empty</a>()</code>.</td> </tr></tbody> </table></div> </li> <li class="listitem"> <pre class="literallayout">function& <a name="idp37708288-bb"></a>operator=(<a class="link" href="functionN.html" title="Class template functionN">functionN</a>&& f);</pre> <div class="variablelist"><table border="0" class="variablelist compact"> <colgroup> <col align="left" valign="top"> <col> </colgroup> <tbody> <tr> <td>Requires:</td> <td>C++11 compatible compiler.</td> </tr> <tr> <td>Postconditions:</td> <td>Moves the value from <code class="computeroutput">f</code> to <code class="computeroutput">*this</code>. If the argument has its function object allocated on the heap, its buffer will be assigned to <code class="computeroutput">*this</code> leaving argument empty.</td> </tr> <tr> <td>Throws:</td> <td>Will not throw unless argument has its function object allocated not on the heap and copying the target of <code class="computeroutput">f</code> throws.</td> </tr> </tbody> </table></div> </li> <li class="listitem"> <pre class="literallayout">function& <a name="idp38571792-bb"></a>operator=(const <a class="link" href="function.html" title="Class template function">function</a>& f);</pre> <div class="variablelist"><table border="0" class="variablelist compact"> <colgroup> <col align="left" valign="top"> <col> </colgroup> <tbody> <tr> <td>Postconditions:</td> <td>If copy construction of the target of <code class="computeroutput">f</code> does not throw, <code class="computeroutput">*this</code> targets a copy of <code class="computeroutput">f</code>'s target, if it has one, or is empty if <code class="computeroutput">f.<a class="link" href="function.html#idp39557232-bb">empty</a>()</code>. </td> </tr> <tr> <td>Throws:</td> <td>Will not throw when the target of <code class="computeroutput">f</code> is a stateless function object or a reference to the function object. If copy construction does throw, <code class="computeroutput">this-><a class="link" href="function.html#idp39557232-bb">empty</a>()</code>.</td> </tr> </tbody> </table></div> </li> <li class="listitem"> <pre class="literallayout">function& <a name="idp105085072-bb"></a>operator=(<a class="link" href="function.html" title="Class template function">function</a>&& f);</pre> <div class="variablelist"><table border="0" class="variablelist compact"> <colgroup> <col align="left" valign="top"> <col> </colgroup> <tbody> <tr> <td>Requires:</td> <td>C++11 compatible compiler.</td> </tr> <tr> <td>Postconditions:</td> <td>Moves the value from <code class="computeroutput">f</code> to <code class="computeroutput">*this</code>. If the argument has its function object allocated on the heap, its buffer will be assigned to <code class="computeroutput">*this</code> leaving argument empty.</td> </tr> <tr> <td>Throws:</td> <td>Will not throw unless argument has its function object allocated not on the heap and copying the target of <code class="computeroutput">f</code> throws.</td> </tr> </tbody> </table></div> </li> <li class="listitem"> <pre class="literallayout"><a name="idp45860512-bb"></a>~function();</pre> <div class="variablelist"><table border="0" class="variablelist compact"> <colgroup> <col align="left" valign="top"> <col> </colgroup> <tbody><tr> <td>Effects:</td> <td>If <code class="computeroutput">!this-><a class="link" href="function.html#idp39557232-bb">empty</a>()</code>, destroys the target of <code class="computeroutput">this</code>.</td> </tr></tbody> </table></div> </li> </ol></div> </div> <div class="refsect2"> <a name="idp210159696"></a><h3> <a name="idp108302096-bb"></a><code class="computeroutput">function</code> modifiers</h3> <div class="orderedlist"><ol class="orderedlist" type="1"> <li class="listitem"> <pre class="literallayout">void <a name="idp108302656-bb"></a>swap(const <a class="link" href="function.html" title="Class template function">function</a>& f);</pre> <div class="variablelist"><table border="0" class="variablelist compact"> <colgroup> <col align="left" valign="top"> <col> </colgroup> <tbody><tr> <td>Effects:</td> <td>Interchanges the targets of <code class="computeroutput">*this</code> and <code class="computeroutput">f</code>.</td> </tr></tbody> </table></div> </li> <li class="listitem"> <pre class="literallayout">void <a name="idp72870112-bb"></a>clear();</pre> <div class="variablelist"><table border="0" class="variablelist compact"> <colgroup> <col align="left" valign="top"> <col> </colgroup> <tbody> <tr> <td>Postconditions:</td> <td><code class="computeroutput">this-><a class="link" href="function.html#idp39557232-bb">empty</a>()</code></td> </tr> <tr> <td>Throws:</td> <td>Will not throw.</td> </tr> </tbody> </table></div> </li> </ol></div> </div> <div class="refsect2"> <a name="idp210178832"></a><h3> <a name="idp99731696-bb"></a><code class="computeroutput">function</code> capacity</h3> <div class="orderedlist"><ol class="orderedlist" type="1"> <li class="listitem"> <pre class="literallayout">bool <a name="idp39557232-bb"></a>empty() const;</pre> <div class="variablelist"><table border="0" class="variablelist compact"> <colgroup> <col align="left" valign="top"> <col> </colgroup> <tbody> <tr> <td>Returns:</td> <td> <code class="computeroutput">false</code> if <code class="computeroutput">this</code> has a target, and <code class="computeroutput">true</code> otherwise.</td> </tr> <tr> <td>Throws:</td> <td>Will not throw.</td> </tr> </tbody> </table></div> </li> <li class="listitem"> <pre class="literallayout"><a name="idp41154480-bb"></a>operator safe_bool() const;</pre> <div class="variablelist"><table border="0" class="variablelist compact"> <colgroup> <col align="left" valign="top"> <col> </colgroup> <tbody> <tr> <td>Returns:</td> <td>A <code class="computeroutput">safe_bool</code> that evaluates <code class="computeroutput">false</code> in a boolean context when <code class="computeroutput">this-><a class="link" href="function.html#idp39557232-bb">empty</a>()</code>, and <code class="computeroutput">true</code> otherwise.</td> </tr> <tr> <td>Throws:</td> <td>Will not throw.</td> </tr> </tbody> </table></div> </li> <li class="listitem"> <pre class="literallayout">bool <a name="idp76193136-bb"></a>operator!() const;</pre> <div class="variablelist"><table border="0" class="variablelist compact"> <colgroup> <col align="left" valign="top"> <col> </colgroup> <tbody> <tr> <td>Returns:</td> <td><code class="computeroutput">this-><a class="link" href="function.html#idp39557232-bb">empty</a>()</code></td> </tr> <tr> <td>Throws:</td> <td>Will not throw.</td> </tr> </tbody> </table></div> </li> </ol></div> </div> <div class="refsect2"> <a name="idp210210176"></a><h3> <a name="idp69032368-bb"></a><code class="computeroutput">function</code> target access</h3> <div class="orderedlist"><ol class="orderedlist" type="1"> <li class="listitem"> <pre class="literallayout"><a name="idp113597248-bb"></a>template<typename Functor> Functor* <a name="idp113597808-bb"></a>target(); template<typename Functor> const Functor* <a name="idp37917680-bb"></a>target() const;</pre> <div class="variablelist"><table border="0" class="variablelist compact"> <colgroup> <col align="left" valign="top"> <col> </colgroup> <tbody> <tr> <td>Returns:</td> <td>If <code class="computeroutput">this</code> stores a target of type <code class="computeroutput">Functor</code>, returns the address of the target. Otherwise, returns the NULL pointer.</td> </tr> <tr> <td>Throws:</td> <td>Will not throw.</td> </tr> </tbody> </table></div> </li> <li class="listitem"> <pre class="literallayout">template<typename Functor> bool <a name="idp44257488-bb"></a>contains(const Functor& f) const;</pre> <div class="variablelist"><table border="0" class="variablelist compact"> <colgroup> <col align="left" valign="top"> <col> </colgroup> <tbody><tr> <td>Returns:</td> <td> <code class="computeroutput">true</code> if <code class="computeroutput">this-><a class="link" href="function.html#idp113597248-bb">target</a><Functor>()</code> is non-NULL and <code class="computeroutput"><a class="link" href="function_equal.html" title="Function template function_equal">function_equal</a>(*(this->target<Functor>()), f)</code> </td> </tr></tbody> </table></div> </li> <li class="listitem"> <pre class="literallayout">const std::type_info& <a name="idp46276608-bb"></a>target_type() const;</pre> <div class="variablelist"><table border="0" class="variablelist compact"> <colgroup> <col align="left" valign="top"> <col> </colgroup> <tbody> <tr> <td>Returns:</td> <td> <code class="computeroutput">typeid</code> of the target function object, or <code class="computeroutput">typeid(void)</code> if <code class="computeroutput">this-><a class="link" href="function.html#idp39557232-bb">empty</a>()</code>.</td> </tr> <tr> <td>Throws:</td> <td>Will not throw.</td> </tr> </tbody> </table></div> </li> </ol></div> </div> <div class="refsect2"> <a name="idp210258608"></a><h3> <a name="idp55139648-bb"></a><code class="computeroutput">function</code> invocation</h3> <div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"> <pre class="literallayout">result_type <a name="idp55140176-bb"></a>operator()(arg1_type a1, arg2_type a2, ..., argN_type aN) const;</pre> <div class="variablelist"><table border="0" class="variablelist compact"> <colgroup> <col align="left" valign="top"> <col> </colgroup> <tbody> <tr> <td>Effects:</td> <td> <code class="computeroutput">f(a1, a2, ..., aN)</code>, where <code class="computeroutput">f</code> is the target of <code class="computeroutput">*this</code>.</td> </tr> <tr> <td>Returns:</td> <td>if <code class="computeroutput">R</code> is <code class="computeroutput">void</code>, nothing is returned; otherwise, the return value of the call to <code class="computeroutput">f</code> is returned.</td> </tr> <tr> <td>Throws:</td> <td> <code class="computeroutput"><a class="link" href="bad_function_call.html" title="Class bad_function_call">bad_function_call</a></code> if <code class="computeroutput">this-><a class="link" href="function.html#idp39557232-bb">empty</a>()</code>. Otherwise, may through any exception thrown by the target function <code class="computeroutput">f</code>.</td> </tr> </tbody> </table></div> </li></ol></div> </div> <div class="refsect2"> <a name="idp210297584"></a><h3> <a name="idp111166064-bb"></a><code class="computeroutput">function</code> specialized algorithms</h3> <div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"> <pre class="literallayout">template<typename Signature> void <a name="boost.function.swap_idp76190448"></a>swap(<a class="link" href="function.html" title="Class template function">function</a><Signature><span clas