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<h3><a href="../../../../index.htm"><img height="86" width="277"
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<h1 align="center"><a href="../index.html">Boost.Python</a></h1>
<h2 align="center">Header <boost/python/def.hpp></h2>
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<h2>Contents</h2>
<dl class="page-index">
<dt><a href="#introduction">Introduction</a></dt>
<dt><a href="#functions">Functions</a></dt>
<dd>
<dl class="page-index">
<dt><a href="#def-spec">def</a></dt>
</dl>
</dd>
<dt><a href="#examples">Example</a></dt>
</dl>
<hr>
<h2><a name="introduction"></a>Introduction</h2>
<p><code><a href="#def-spec">def</a>()</code> is the function which can
be used to expose C++ functions and callable objects as Python functions
in the current <code><a href="scope.html">scope</a></code>.</p>
<h2><a name="functions"></a>Functions</h2>
<a name="def-spec"></a>def
<pre>
template <class F>
void def(char const* name, F f);
template <class Fn, class A1>
void def(char const* name, Fn fn, A1 const&);
template <class Fn, class A1, class A2>
void def(char const* name, Fn fn, A1 const&, A2 const&);
template <class Fn, class A1, class A2, class A3>
void def(char const* name, Fn fn, A1 const&, A2 const&, A3 const&);
</pre>
<dl class="function-semantics">
<dt><b>Requires:</b> <code>name</code> is an <a href=
"definitions.html#ntbs">ntbs</a> which conforms to Python's <a href=
"http://www.python.org/doc/current/ref/identifiers.html">identifier
naming rules</a>.</dt>
<dd>
<ul>
<li>If <code>Fn</code> is [derived from] <code><a href=
"object.html#object-spec">object</a></code>, it will be added to
the current scope as a single overload. To be useful,
<code>fn</code> should be <a href=
"http://www.python.org/doc/current/lib/built-in-funcs.html#l2h-6">callable</a>.</li>
<li>
If <code>a1</code> is the result of an <a href=
"overloads.html#overload-dispatch-expression"><em>overload-dispatch-expression</em></a>,
only the second form is allowed and fn must be a pointer to
function or pointer to member function whose <a href=
"definitions.html#arity">arity</a> is the same as A1's <a href=
"overloads.html#overload-dispatch-expression"><em>maximum
arity</em></a>.
<dl>
<dt><b>Effects:</b> For each prefix <em>P</em> of
<code>Fn</code>'s sequence of argument types, beginning with
the one whose length is <code>A1</code>'s <a href=
"overloads.html#overload-dispatch-expression"><em>minimum
arity</em></a>, adds a
<code><em>name</em>(</code>...<code>)</code> function overload
to the <a href="scope.html">current scope</a>. Each overload
generated invokes <code>a1</code>'s call-expression with
<em>P</em>, using a copy of <code>a1</code>'s <a href=
"CallPolicies.html">call policies</a>. If the longest valid
prefix of <code>A1</code> contains <em>N</em> types and
<code>a1</code> holds <em>M</em> keywords, an initial sequence
of the keywords are used for all but the first
<em>N</em> - <em>M</em> arguments of each
overload.<br>
</dt>
</dl>
</li>
<li>Otherwise, fn must be a non-null function or member function
pointer, and a single function overload built around fn is added to
the <a href="scope.html">current scope</a>. If any of
<code>a1</code>-<code>a3</code> are supplied, they may be selected
in any order from the table below.</li>
</ul>
<table border="1" summary="def() optional arguments">
<tr>
<th>Memnonic Name</th>
<th>Requirements/Type properties</th>
<th>Effects</th>
</tr>
<tr>
<td>docstring</td>
<td>Any <a href="definitions.html#ntbs">ntbs</a>.</td>
<td>Value will be bound to the <code>__doc__</code> attribute of
the resulting method overload.</td>
</tr>
<tr>
<td>policies</td>
<td>A model of <a href="CallPolicies.html">CallPolicies</a></td>
<td>A copy will be used as the call policies of the resulting
method overload.</td>
</tr>
<tr>
<td>keywords</td>
<td>The result of a <a href=
"args.html#keyword-expression"><em>keyword-expression</em></a>
specifying no more arguments than the <a href=
"definitions.html#arity">arity</a> of <code>fn</code>.</td>
<td>A copy will be used as the call policies of the resulting
method overload.</td>
</tr>
</table>
</dd>
</dl>
<h2><a name="examples"></a>Example</h2>
<pre>
#include <boost/python/def.hpp>
#include <boost/python/module.hpp>
#include <boost/python/args.hpp>
using namespace boost::python;
char const* foo(int x, int y) { return "foo"; }
BOOST_PYTHON_MODULE(def_test)
{
def("foo", foo, args("x", "y"), "foo's docstring");
}
</pre>
<p>
<!--webbot bot="Timestamp" S-Type="EDITED" S-Format="%d %B, %Y" startspan -->
7 March, 2003
<!--webbot bot="Timestamp" endspan i-checksum="39359" -->
</p>
<p><i>© Copyright <a href=
"http://www.boost.org/people/dave_abrahams.htm">Dave Abrahams</a> 2002.</i></p>
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