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<h1 align="center"><a href="../index.html">Boost.Python</a></h1>
<h2 align="center">Header &lt;boost/python/object.hpp&gt;</h2>
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<hr>
<h2>Contents</h2>
<dl class="page-index">
<dt><a href="#introduction">Introduction</a></dt>
<dt><a href="#types">Types</a></dt>
<dd>
<dl class="page-index">
<dt><a href="#slice_nil-spec">slice_nil</a></dt>
</dl>
</dd>
<dt><a href="#classes">Classes</a></dt>
<dd>
<dl class="page-index">
<dt><a href="#const_attribute_policies-spec">Class
<code>const_attribute_policies</code></a></dt>
<dd>
<dl class="page-index">
<dt><a href="#const_attribute_policies-spec-synopsis">Class
<code>const_attribute_policies</code> synopsis</a></dt>
<dt><a href="#const_attribute_policies-spec-statics">Class
<code>const_attribute_policies</code> static functions</a></dt>
</dl>
</dd>
<dt><a href="#attribute_policies-spec">Class
<code>attribute_policies</code></a></dt>
<dd>
<dl class="page-index">
<dt><a href="#attribute_policies-spec-synopsis">Class
<code>attribute_policies</code> synopsis</a></dt>
<dt><a href="#attribute_policies-spec-statics">Class
<code>attribute_policies</code> static functions</a></dt>
</dl>
</dd>
<dt><a href="#const_objattribute_policies-spec">Class
<code>const_objattribute_policies</code></a></dt>
<dd>
<dl class="page-index">
<dt><a href="#const_objattribute_policies-spec-synopsis">Class
<code>const_objattribute_policies</code> synopsis</a></dt>
<dt><a href="#const_objattribute_policies-spec-statics">Class
<code>const_objattribute_policies</code> static functions</a></dt>
</dl>
</dd>
<dt><a href="#objattribute_policies-spec">Class
<code>objattribute_policies</code></a></dt>
<dd>
<dl class="page-index">
<dt><a href="#objattribute_policies-spec-synopsis">Class
<code>objattribute_policies</code> synopsis</a></dt>
<dt><a href="#objattribute_policies-spec-statics">Class
<code>objattribute_policies</code> static functions</a></dt>
</dl>
</dd>
<dt><a href="#const_item_policies-spec">Class
<code>const_item_policies</code></a></dt>
<dd>
<dl class="page-index">
<dt><a href="#const_item_policies-spec-synopsis">Class
<code>const_item_policies</code> synopsis</a></dt>
<dt><a href="#const_item_policies-spec-statics">Class
<code>const_item_policies</code> static functions</a></dt>
</dl>
</dd>
<dt><a href="#item_policies-spec">Class
<code>item_policies</code></a></dt>
<dd>
<dl class="page-index">
<dt><a href="#item_policies-spec-synopsis">Class
<code>item_policies</code> synopsis</a></dt>
<dt><a href="#item_policies-spec-statics">Class
<code>item_policies</code> static functions</a></dt>
</dl>
</dd>
<dt><a href="#const_slice_policies-spec">Class
<code>const_slice_policies</code></a></dt>
<dd>
<dl class="page-index">
<dt><a href="#const_slice_policies-spec-synopsis">Class
<code>const_slice_policies</code> synopsis</a></dt>
<dt><a href="#const_slice_policies-spec-statics">Class
<code>const_slice_policies</code> static functions</a></dt>
</dl>
</dd>
<dt><a href="#slice_policies-spec">Class
<code>slice_policies</code></a></dt>
<dd>
<dl class="page-index">
<dt><a href="#slice_policies-spec-synopsis">Class
<code>slice_policies</code> synopsis</a></dt>
<dt><a href="#slice_policies-spec-statics">Class
<code>slice_policies</code> static functions</a></dt>
</dl>
</dd>
<dt><a href="#object_operators-spec">Class
<code>object_operators</code></a></dt>
<dd>
<dl class="page-index">
<dt><a href="#object_operators-spec-synopsis">Class
<code>object_operators</code> synopsis</a></dt>
<dt><a href="#object_operators-spec-observers">Class
<code>object_operators</code> observer functions</a></dt>
</dl>
</dd>
<dt><a href="#object-spec">Class <code>object</code></a></dt>
<dd>
<dl class="page-index">
<dt><a href="#object-spec-synopsis">Class <code>object</code>
synopsis</a></dt>
<dt><a href="#object-spec-ctors">Class <code>object</code>
constructors and destructor</a></dt>
<dt><a href="#object-spec-modifiers">Class template
<code>object</code> modifier functions</a></dt>
<dt><a href="#object-spec-observers">Class template
<code>object</code> observer functions</a></dt>
</dl>
</dd>
<dt><a href="#proxy-spec">Class template
<code>proxy</code></a></dt>
<dd>
<dl class="page-index">
<dt><a href="#proxy-spec-synopsis">Class template
<code>proxy</code> synopsis</a></dt>
<dt><a href="#proxy-spec-modifiers">Class template
<code>proxy</code> modifier functions</a></dt>
<dt><a href="#proxy-spec-observers">Class template
<code>proxy</code> observer functions</a></dt>
</dl>
</dd>
</dl>
</dd>
<dt><a href="#functions">Functions</a></dt>
<dd>
<dl class="page-index">
<dt><a href="#del-spec">del</a></dt>
<dt><a href="#comparisons-spec">comparisons</a></dt>
<dt><a href="#binary-spec">binary operations</a></dt>
<dt><a href="#assignment-spec">assignment operations</a></dt>
</dl>
<dl class="page-index">
<dt><a href="#object_operators-spec">operators</a></dt>
</dl>
<dl class="page-index">
<dt><a href="#len-spec">len()</a></dt>
</dl>
</dd>
<dt><a href="#examples">Example</a></dt>
</dl>
<hr>
<h2><a name="introduction"></a>Introduction</h2>
<p>Exposes the generic Python object wrapper class <code>object</code>,
and related classes. In order to avoid some potenential problems with
argument-dependent lookup and the generalized operators defined on
<code>object</code>, all these facilities are defined in
<code>namespace&nbsp;boost::python::api</code>, and <code>object</code>
is imported into <code>namespace&nbsp;boost::python</code> with a
<i>using-declaration</i>.</p>
<h2><a name="types"></a>Types</h2>
<p><a name="slice_nil-spec"></a></p>
<pre>
class slice_nil;
static const _ = slice_nil();
</pre>
A type that can be used to get the effect of leaving out an index in a
Python slice expression:
<pre>
&gt;&gt;&gt; x[:-1]
&gt;&gt;&gt; x[::-1]
</pre>
C++ equivalent:
<pre>
x.slice(_,-1)
x[slice(_,_,-1)]
</pre>
<h2><a name="classes"></a>Classes</h2>
<!-- begin -->
<h3><a name="const_attribute_policies-spec"></a>Class
<code>const_attribute_policies</code></h3>
<p>The policies which are used for proxies representing an attribute
access to a <code>const&nbsp;object</code>.</p>
<h4><a name="const_attribute_policies-spec-synopsis"></a>Class
<code>const_attribute_policies</code> synopsis</h4>
<pre>
namespace boost { namespace python { namespace api
{
struct const_attribute_policies
{
typedef char const* key_type;
static object get(object const&amp; target, char const* key);
};
}}}
</pre>
<h4><a name="const_attribute_policies-spec-statics"></a>Class
<code>const_attribute_policies</code> static functions</h4>
<pre>
static object get(object const&amp; target, char const* key);
</pre>
<dl class="function-semantics">
<dt><b>Requires:</b> <code>key</code> is an <a href=
"definitions.html#ntbs">ntbs</a>.</dt>
<dt><b>Effects:</b> accesses the attribute of <code>target</code> named
by <code>key</code>.</dt>
<dt><b>Returns:</b> An <code>object</code> managing the result of the
attribute access.</dt>
<dt><b>Throws:</b> <code><a href=
"errors.html#error_already_set-spec">error_already_set</a></code> if a
Python exception is raised.</dt>
</dl>
<h3><a name="attribute_policies-spec"></a>Class
<code>attribute_policies</code></h3>
<p>The policies which are used for proxies representing an attribute
access to a mutable <code>object</code>.</p>
<h4><a name="attribute_policies-spec-synopsis"></a>Class
<code>attribute_policies</code> synopsis</h4>
<pre>
namespace boost { namespace python { namespace api
{
struct attribute_policies : const_attribute_policies
{
static object const&amp; set(object const&amp; target, char const* key, object const&amp; value);
static void del(object const&amp;target, char const* key);
};
}}}
</pre>
<h4><a name="attribute_policies-spec-statics"></a>Class
<code>attribute_policies</code> static functions</h4>
<pre>
static object const&amp; set(object const&amp; target, char const* key, object const&amp; value);
</pre>
<dl class="function-semantics">
<dt><b>Requires:</b> <code>key</code> is an <a href=
"definitions.html#ntbs">ntbs</a>.</dt>
<dt><b>Effects:</b> sets the attribute of <code>target</code> named by
<code>key</code> to <code>value</code>.</dt>
<dt><b>Throws:</b> <code><a href=
"errors.html#error_already_set-spec">error_already_set</a></code> if a
Python exception is raised.</dt>
</dl>
<pre>
static void del(object const&amp;target, char const* key);
</pre>
<dl class="function-semantics">
<dt><b>Requires:</b> <code>key</code> is an <a href=
"definitions.html#ntbs">ntbs</a>.</dt>
<dt><b>Effects:</b> deletes the attribute of <code>target</code> named
by <code>key</code>.</dt>
<dt><b>Throws:</b> <code><a href=
"errors.html#error_already_set-spec">error_already_set</a></code> if a
Python exception is raised.</dt>
</dl>
<!-- end -->
<!-- begin -->
<h3><a name="const_objattribute_policies-spec"></a>Class
<code>const_objattribute_policies</code></h3>
<p>The policies which are used for proxies representing an attribute
access to a <code>const&nbsp;object</code> when the attribute name is
given as a <code>const&nbsp;object</code>.</p>
<h4><a name="const_objattribute_policies-spec-synopsis"></a>Class
<code>const_objattribute_policies</code> synopsis</h4>
<pre>
namespace boost { namespace python { namespace api
{
struct const_objattribute_policies
{
typedef object const& key_type;
static object get(object const&amp; target, object const& key);
};
}}}
</pre>
<h4><a name="const_objattribute_policies-spec-statics"></a>Class
<code>const_objattribute_policies</code> static functions</h4>
<pre>
static object get(object const&amp; target, object const& key);
</pre>
<dl class="function-semantics">
<dt><b>Requires:</b> <code>key</code> is an <code>object</code>
holding a string.</dt>
<dt><b>Effects:</b> accesses the attribute of <code>target</code> named
by <code>key</code>.</dt>
<dt><b>Returns:</b> An <code>object</code> managing the result of the
attribute access.</dt>
<dt><b>Throws:</b> <code><a href=
"errors.html#error_already_set-spec">error_already_set</a></code> if a
Python exception is raised.</dt>
</dl>
<h3><a name="objattribute_policies-spec"></a>Class
<code>objattribute_policies</code></h3>
<p>The policies which are used for proxies representing an attribute
access to a mutable <code>object</code> when the attribute name is
given as a <code>const&nbsp;object</code>.</p>
<h4><a name="objattribute_policies-spec-synopsis"></a>Class
<code>objattribute_policies</code> synopsis</h4>
<pre>
namespace boost { namespace python { namespace api
{
struct objattribute_policies : const_objattribute_policies
{
static object const&amp; set(object const&amp; target, object const& key, object const&amp; value);
static void del(object const&amp;target, object const& key);
};
}}}
</pre>
<h4><a name="objattribute_policies-spec-statics"></a>Class
<code>objattribute_policies</code> static functions</h4>
<pre>
static object const&amp; set(object const&amp; target, object const& key, object const&amp; value);
</pre>
<dl class="function-semantics">
<dt><b>Requires:</b> <code>key</code> is an <code>object</code>
holding a string.</dt>
<dt><b>Effects:</b> sets the attribute of <code>target</code> named by
<code>key</code> to <code>value</code>.</dt>
<dt><b>Throws:</b> <code><a href=
"errors.html#error_already_set-spec">error_already_set</a></code> if a
Python exception is raised.</dt>
</dl>
<pre>
static void del(object const&amp;target, object const& key);
</pre>
<dl class="function-semantics">
<dt><b>Requires:</b> <code>key</code> is an <code>object</code>
holding a string.</dt>
<dt><b>Effects:</b> deletes the attribute of <code>target</code> named
by <code>key</code>.</dt>
<dt><b>Throws:</b> <code><a href=
"errors.html#error_already_set-spec">error_already_set</a></code> if a
Python exception is raised.</dt>
</dl>
<!-- end -->
<!-- begin -->
<h3><a name="const_item_policies-spec"></a>Class
<code>const_item_policies</code></h3>
<p>The policies which are used for proxies representing an item access
(via the Python bracket operators <code>[]</code>) to a
<code>const&nbsp;object</code>.</p>
<h4><a name="const_item_policies-spec-synopsis"></a>Class
<code>const_item_policies</code> synopsis</h4>
<pre>
namespace boost { namespace python { namespace api
{
struct const_item_policies
{
typedef object key_type;
static object get(object const&amp; target, object const&amp; key);
};
}}}
</pre>
<h4><a name="const_item_policies-spec-statics"></a>Class
<code>const_item_policies</code> static functions</h4>
<pre>
static object get(object const&amp; target, object const&amp; key);
</pre>
<dl class="function-semantics">
<dt><b>Effects:</b> accesses the item of <code>target</code> specified
by <code>key</code>.</dt>
<dt><b>Returns:</b> An <code>object</code> managing the result of the
item access.</dt>
<dt><b>Throws:</b> <code><a href=
"errors.html#error_already_set-spec">error_already_set</a></code> if a
Python exception is raised.</dt>
</dl>
<h3><a name="item_policies-spec"></a>Class
<code>item_policies</code></h3>
<p>The policies which are used for proxies representing an item access
(via the Python bracket operators <code>[]</code>) to a mutable
<code>object</code>.</p>
<h4><a name="item_policies-spec-synopsis"></a>Class
<code>item_policies</code> synopsis</h4>
<pre>
namespace boost { namespace python { namespace api
{
struct item_policies : const_item_policies
{
static object const&amp; set(object const&amp; target, object const&amp; key, object const&amp; value);
static void del(object const&amp; target, object const&amp; key);
};
}}}
</pre>
<h4><a name="item_policies-spec-statics"></a>Class
<code>item_policies</code> static functions</h4>
<pre>
static object const&amp; set(object const&amp; target, object const&amp; key, object const&amp; value);
</pre>
<dl class="function-semantics">
<dt><b>Effects:</b> sets the item of <code>target</code> specified by
<code>key</code> to <code>value</code>.</dt>
<dt><b>Throws:</b> <code><a href=
"errors.html#error_already_set-spec">error_already_set</a></code> if a
Python exception is raised.</dt>
</dl>
<pre>
static void del(object const&amp; target, object const&amp; key);
</pre>
<dl class="function-semantics">
<dt><b>Effects:</b> deletes the item of <code>target</code> specified
by <code>key</code>.</dt>
<dt><b>Throws:</b> <code><a href=
"errors.html#error_already_set-spec">error_already_set</a></code> if a
Python exception is raised.</dt>
</dl>
<!-- end -->
<!-- begin -->
<h3><a name="const_slice_policies-spec"></a>Class
<code>const_slice_policies</code></h3>
<p>The policies which are used for proxies representing an slice access
(via the Python slice notation
<code>[</code><i>x</i><code>:</code><i>y</i><code>]</code>) to a
<code>const&nbsp;object</code>.</p>
<h4><a name="const_slice_policies-spec-synopsis"></a>Class
<code>const_slice_policies</code> synopsis</h4>
<pre>
namespace boost { namespace python { namespace api
{
struct const_slice_policies
{
typedef std::pair&lt;handle&lt;&gt;, handle&lt;&gt; &gt; key_type;
static object get(object const&amp; target, key_type const&amp; key);
};
}}}
</pre>
<h4><a name="const_slice_policies-spec-statics"></a>Class
<code>const_slice_policies</code> static functions</h4>
<pre>
static object get(object const&amp; target, key_type const&amp; key);
</pre>
<dl class="function-semantics">
<dt><b>Effects:</b> accesses the slice of <code>target</code> specified
by <code>key</code>.</dt>
<dt><b>Returns:</b> An <code>object</code> managing the result of the
slice access.</dt>
<dt><b>Throws:</b> <code><a href=
"errors.html#error_already_set-spec">error_already_set</a></code> if a
Python exception is raised.</dt>
</dl>
<h3><a name="slice_policies-spec"></a>Class
<code>slice_policies</code></h3>
<p>The policies which are used for proxies representing an slice access
to a mutable <code>object</code>.</p>
<h4><a name="slice_policies-spec-synopsis"></a>Class
<code>slice_policies</code> synopsis</h4>
<pre>
namespace boost { namespace python { namespace api
{
struct slice_policies : const_slice_policies
{
static object const&amp; set(object const&amp; target, key_type const&amp; key, object const&amp; value);
static void del(object const&amp; target, key_type const&amp; key);
};
}}}
</pre>
<h4><a name="slice_policies-spec-statics"></a>Class
<code>slice_policies</code> static functions</h4>
<pre>
static object const&amp; set(object const&amp; target, key_type const&amp; key, object const&amp; value);
</pre>
<dl class="function-semantics">
<dt><b>Effects:</b> sets the slice of <code>target</code> specified by
<code>key</code> to <code>value</code>.</dt>
<dt><b>Throws:</b> <code><a href=
"errors.html#error_already_set-spec">error_already_set</a></code> if a
Python exception is raised.</dt>
</dl>
<pre>
static void del(object const&amp; target, key_type const&amp; key);
</pre>
<dl class="function-semantics">
<dt><b>Effects:</b> deletes the slice of <code>target</code> specified
by <code>key</code>.</dt>
<dt><b>Throws:</b> <code><a href=
"errors.html#error_already_set-spec">error_already_set</a></code> if a
Python exception is raised.</dt>
</dl>
<!-- end -->
<h3><a name="object_operators-spec"></a>Class template
<code>object_operators&lt;U&gt;</code></h3>
<p>This is the base class of <code>object</code> and its
<code>proxy</code> template used to supply common interface: member
functions, and operators which must be defined within the class body. Its
template parameter <code>U</code> is expected to be a class derived from
<code>object_operators&lt;U&gt;</code>. In practice users should never
use this class directly, but it is documented here because it supplies
important interface to <code>object</code> and its proxies.</p>
<h4><a name="object_operators-spec-synopsis"></a>Class template
<code>object_operators</code> synopsis</h4>
<pre>
namespace boost { namespace python { namespace api
{
template &lt;class U&gt;
class object_operators
{
public:
// function call
//
object operator()() const;
template &lt;class A0&gt;
object operator()(A0 const&amp;) const;
template &lt;class A0, class A1&gt;
object operator()(A0 const&amp;, A1 const&amp;) const;
...
template &lt;class A0, class A1,...class An&gt;
object operator()(A0 const&amp;, A1 const&amp;,...An const&amp;) const;
detail::args_proxy operator* () const;
object operator()(detail::args_proxy const &amp;args) const;
object operator()(detail::args_proxy const &amp;args,
detail::kwds_proxy const &amp;kwds) const;
// truth value testing
//
typedef unspecified bool_type;
operator bool_type() const;
// Attribute access
//
proxy&lt;const_object_attribute&gt; attr(char const*) const;
proxy&lt;object_attribute&gt; attr(char const*);
proxy&lt;const_object_objattribute&gt; attr(object const&) const;
proxy&lt;object_objattribute&gt; attr(object const&);
// item access
//
template &lt;class T&gt;
proxy&lt;const_object_item&gt; operator[](T const&amp; key) const;
template &lt;class T&gt;
proxy&lt;object_item&gt; operator[](T const&amp; key);
// slicing
//
template &lt;class T, class V&gt;
proxy&lt;const_object_slice&gt; slice(T const&amp; start, V const&amp; end) const
template &lt;class T, class V&gt;
proxy&lt;object_slice&gt; slice(T const&amp; start, V const&amp; end);
};
}}}
</pre>
<h4><a name="object_operators-spec-observers"></a>Class template
<code>object_operators</code> observer functions</h4>
<pre>
object operator()() const;
template &lt;class A0&gt;
object operator()(A0 const&amp;) const;
template &lt;class A0, class A1&gt;
object operator()(A0 const&amp;, A1 const&amp;) const;
...
template &lt;class A0, class A1,...class An&gt;
object operator()(A0 const&amp; a1, A1 const&amp; a2,...An const&amp; aN) const;
</pre>
<dl class="function-semantics">
<dt><b>Effects:</b>
call&lt;object&gt;(object(*static_cast&lt;U*&gt;(this)).ptr(), a1,
a2,...aN)</dt>
</dl>
<pre>
object operator()(detail::args_proxy const &amp;args) const;
</pre>
<dl class="function-semantics">
<dt><b>Effects:</b>
call object with arguments given by the tuple <varname>args</varname></dt>
</dl>
<pre>
object operator()(detail::args_proxy const &amp;args,
detail::kwds_proxy const &amp;kwds) const;
</pre>
<dl class="function-semantics">
<dt><b>Effects:</b>
call object with arguments given by the tuple <varname>args</varname>, and named
arguments given by the dictionary <varname>kwds</varname></dt>
</dl>
<pre>
operator bool_type() const;
</pre>
<dl class="function-semantics">
<dt><b>Effects:</b> Tests truth value of <code>*this</code>.</dt>
<dt><b>Returns:</b>
call&lt;object&gt;(object(*static_cast&lt;U*&gt;(this)).ptr(), a1,
a2,...aN)</dt>
</dl>
<pre>
proxy&lt;const_object_attribute&gt; attr(char const* name) const;
proxy&lt;object_attribute&gt; attr(char const* name);
</pre>
<dl class="function-semantics">
<dt><b>Requires:</b> name is an <a href=
"definitions.html#ntbs">ntbs</a>.</dt>
<dt><b>Effects:</b> accesses the named attribute of
<code>*this</code>.</dt>
<dt><b>Returns:</b> a proxy object which binds
<code>object(*static_cast&lt;U*&gt;(this))</code> as its target, and
<code>name</code> as its key.</dt>
</dl>
<pre>
proxy&lt;const_object_objattribute&gt; attr(const object& name) const;
proxy&lt;object_objattribute&gt; attr(const object& name);
</pre>
<dl class="function-semantics">
<dt><b>Requires:</b> name is a <code>object</code> holding a string.</dt>
<dt><b>Effects:</b> accesses the named attribute of
<code>*this</code>.</dt>
<dt><b>Returns:</b> a proxy object which binds
<code>object(*static_cast&lt;U*&gt;(this))</code> as its target, and
<code>name</code> as its key.</dt>
</dl>
<pre>
template &lt;class T&gt;
proxy&lt;const_object_item&gt; operator[](T const&amp; key) const;
template &lt;class T&gt;
proxy&lt;object_item&gt; operator[](T const&amp; key);
</pre>
<dl class="function-semantics">
<dt><b>Effects:</b> accesses the item of <code>*this</code> indicated
by <code>key</code>.</dt>
<dt><b>Returns:</b> a proxy object which binds
<code>object(*static_cast&lt;U*&gt;(this))</code> as its target, and
<code>object(key)</code> as its key.</dt>
</dl>
<pre>
template &lt;class T, class V&gt;
proxy&lt;const_object_slice&gt; slice(T const&amp; start; start, V const&amp; finish) const
template &lt;class T, class V&gt;
proxy&lt;object_slice&gt; slice(T const&amp; start; start, V const&amp; finish);
</pre>
<dl class="function-semantics">
<dt><b>Effects:</b> accesses the slice of <code>*this</code> indicated
by <code>std::make_pair(object(start), object(finish))</code>.</dt>
<dt><b>Returns:</b> a proxy object which binds
<code>object(*static_cast&lt;U*&gt;(this))</code> as its target, and
<code>std::make_pair(object(start), object(finish))</code> as its
key.</dt>
</dl>
<!-- -->
<h3><a name="object-spec"></a>Class <code>object</code></h3>
<p>The intention is that <code>object</code> acts as much like a
Python variable as possible. Thus expressions you'd expect to work
in Python should generally work in the same way from C++. Most of
<code>object</code>'s interface is provided by its base class
<code><a
href="#object_operators-spec">object_operators</a>&lt;object&gt;</code>,
and the <a href="#functions">free functions</a> defined in this
header.
</p>
<h4><a name="object-spec-synopsis"></a>Class <code>object</code>
synopsis</h4>
<pre>
namespace boost { namespace python { namespace api
{
class object : public object_operators&lt;object&gt;
{
public:
object();
object(object const&amp;);
template &lt;class T&gt;
explicit object(T const&amp; x);
~object();
object&amp; operator=(object const&amp;);
PyObject* ptr() const;
bool is_none() const;
};
}}}
</pre>
<h4><a name="object-spec-ctors"></a>Class <code>object</code>
constructors and destructor</h4>
<pre>
object();
</pre>
<dl class="function-semantics">
<dt><b>Effects:</b> Constructs an object managing a reference to the
Python <code>None</code> object.</dt>
<dt><b>Throws:</b> nothing.</dt>
</dl>
<pre>
template &lt;class T&gt;
explicit object(T const&amp; x);
</pre>
<dl class="function-semantics">
<dt><b>Effects:</b> converts <code>x</code> to python and manages a
reference to it.</dt>
<dt><b>Throws:</b> <code>error_already_set</code> and sets a Python
<code>TypeError</code> exception if no such conversion is
possible.</dt>
</dl>
<pre>
~object();
</pre>
<dl class="function-semantics">
<dt><b>Effects:</b> decrements the reference count of the
internally-held object.</dt>
</dl>
<h4><a name="object-spec-modifiers"></a>Class <code>object</code>
modifiers</h4>
<pre>
object&amp; operator=(object const&amp; rhs);
</pre>
<dl class="function-semantics">
<dt><b>Effects:</b> increments the reference count of the object held
by <code>rhs</code> and decrements the reference count of the object
held by <code>*this</code>.</dt>
</dl>
<h4><a name="object-spec-observers"></a>Class <code>object</code>
observers</h4>
<pre>
PyObject* ptr() const;
</pre>
<dl class="function-semantics">
<dt><b>Returns:</b> a pointer to the internally-held Python
object.</dt>
</dl>
<pre>
bool is_none() const;
</pre>
<dl class="function-semantics">
<dt><b>Returns:</b> result of (ptr() == Py_None)</dt>
</dl>
<!-- -->
<h3><a name="proxy-spec"></a>Class template <code>proxy</code></h3>
<p>This template is instantiated with various Policies described in this
document in order to implement attribute, item, and slice access for
<code>object</code>. It stores an object of type
<code>Policies::key_type</code>.</p>
<h4><a name="proxy-spec-synopsis"></a>Class template <code>proxy</code>
synopsis</h4>
<pre>
namespace boost { namespace python { namespace api
{
template &lt;class Policies&gt;
class proxy : public object_operators&lt;proxy&lt;Policies&gt; &gt;
{
public:
operator object() const;
proxy const&amp; operator=(proxy const&amp;) const;
template &lt;class T&gt;
inline proxy const&amp; operator=(T const&amp; rhs) const;
void del() const;
template &lt;class R&gt;
proxy operator+=(R const&amp; rhs);
template &lt;class R&gt;
proxy operator-=(R const&amp; rhs);
template &lt;class R&gt;
proxy operator*=(R const&amp; rhs);
template &lt;class R&gt;
proxy operator/=(R const&amp; rhs);
template &lt;class R&gt;
proxy operator%=(R const&amp; rhs);
template &lt;class R&gt;
proxy operator&lt;&lt;=(R const&amp; rhs);
template &lt;class R&gt;
proxy operator&gt;&gt;=(R const&amp; rhs);
template &lt;class R&gt;
proxy operator&amp;=(R const&amp; rhs);
template &lt;class R&gt;
proxy operator|=(R const&amp; rhs);
};
}}}
</pre>
<h4><a name="proxy-spec-observers"></a>Class template <code>proxy</code>
observer functions</h4>
<pre>
operator object() const;
</pre>
<dl class="function-semantics">
<dt><b>Effects:</b> applies
<code>Policies::get(</code><i>target</i><code>,</code>&nbsp;<i>key</i>
<code>)</code> with the proxy's target and key objects.</dt>
</dl>
<h4><a name="proxy-spec-modifiers"></a>Class template <code>proxy</code>
modifier functions</h4>
<pre>
proxy const&amp; operator=(proxy const&amp; rhs) const;
template &lt;class T&gt;
inline proxy const&amp; operator=(T const&amp; rhs) const;
</pre>
<dl class="function-semantics">
<dt><b>Effects:</b>
<code>Policies::set(</code><i>target</i><code>,</code>&nbsp;<i>key</i>
<code>,&nbsp;object(rhs))</code> with the proxy's target and key
objects.</dt>
</dl>
<pre>
template &lt;class R&gt;
proxy operator+=(R const&amp; rhs);
template &lt;class R&gt;
proxy operator-=(R const&amp; rhs);
template &lt;class R&gt;
proxy operator*=(R const&amp; rhs);
template &lt;class R&gt;
proxy operator/=(R const&amp; rhs);
template &lt;class R&gt;
proxy operator%=(R const&amp; rhs);
template &lt;class R&gt;
proxy operator&lt;&lt;=(R const&amp; rhs);
template &lt;class R&gt;
proxy operator&gt;&gt;=(R const&amp; rhs);
template &lt;class R&gt;
proxy operator&amp;=(R const&amp; rhs);
template &lt;class R&gt;
proxy operator|=(R const&amp; rhs);
</pre>
<dl class="function-semantics">
<dt><b>Effects:</b> for a given operator@=,
<code>object(*this)&nbsp;@=&nbsp;rhs;</code></dt>
<dt><b>Returns:</b> <code>*this</code></dt>
</dl>
<pre>
void del() const;
</pre>
<dl class="function-semantics">
<dt><b>Effects:</b>
<code>Policies::del(</code><i>target</i><code>,</code>&nbsp;<i>key</i>
<code>)</code> with the proxy's target and key objects.</dt>
</dl>
<!-- -->
<h2><a name="functions"></a>Functions</h2>
<pre>
<a name="del-spec"></a>template &lt;class T&gt;
void del(proxy&lt;T&gt; const&amp; x);
</pre>
<dl class="function-semantics">
<dt><b>Effects:</b> x.del()</dt>
</dl>
<pre>
<a name="comparisons-spec"></a>
template&lt;class L,class R&gt; object operator&gt;(L const&amp;l,R const&amp;r);
template&lt;class L,class R&gt; object operator&gt;=(L const&amp;l,R const&amp;r);
template&lt;class L,class R&gt; object operator&lt;(L const&amp;l,R const&amp;r);
template&lt;class L,class R&gt; object operator&lt;=(L const&amp;l,R const&amp;r);
template&lt;class L,class R&gt; object operator==(L const&amp;l,R const&amp;r);
template&lt;class L,class R&gt; object operator!=(L const&amp;l,R const&amp;r);
</pre>
<dl class="function-semantics">
<dt><b>Effects:</b> returns the result of applying the operator to
<code>object(l)</code> and <code>object(r)</code>, respectively, in
Python.</dt>
</dl>
<pre>
<a name="binary-spec"></a>
template&lt;class L,class R&gt; object operator+(L const&amp;l,R const&amp;r);
template&lt;class L,class R&gt; object operator-(L const&amp;l,R const&amp;r);
template&lt;class L,class R&gt; object operator*(L const&amp;l,R const&amp;r);
template&lt;class L,class R&gt; object operator/(L const&amp;l,R const&amp;r);
template&lt;class L,class R&gt; object operator%(L const&amp;l,R const&amp;r);
template&lt;class L,class R&gt; object operator&lt;&lt;(L const&amp;l,R const&amp;r);
template&lt;class L,class R&gt; object operator&gt;&gt;(L const&amp;l,R const&amp;r);
template&lt;class L,class R&gt; object operator&amp;(L const&amp;l,R const&amp;r);
template&lt;class L,class R&gt; object operator^(L const&amp;l,R const&amp;r);
template&lt;class L,class R&gt; object operator|(L const&amp;l,R const&amp;r);
</pre>
<dl class="function-semantics">
<dt><b>Effects:</b> returns the result of applying the operator to
<code>object(l)</code> and <code>object(r)</code>, respectively, in
Python.</dt>
</dl>
<pre>
<a name="assignment-spec"></a>
template&lt;class R&gt; object&amp; operator+=(object&amp;l,R const&amp;r);
template&lt;class R&gt; object&amp; operator-=(object&amp;l,R const&amp;r);
template&lt;class R&gt; object&amp; operator*=(object&amp;l,R const&amp;r);
template&lt;class R&gt; object&amp; operator/=(object&amp;l,R const&amp;r);
template&lt;class R&gt; object&amp; operator%=(object&amp;l,R const&amp;r);
template&lt;class R&gt; object&amp; operator&lt;&lt;=(object&amp;l,R const&amp;r)
template&lt;class R&gt; object&amp; operator&gt;&gt;=(object&amp;l,R const&amp;r);
template&lt;class R&gt; object&amp; operator&amp;=(object&amp;l,R const&amp;r);
template&lt;class R&gt; object&amp; operator^=(object&amp;l,R const&amp;r);
template&lt;class R&gt; object&amp; operator|=(object&amp;l,R const&amp;r);
</pre>
<dl class="function-semantics">
<dt><b>Effects:</b> assigns to l the result of applying the
corresponding Python inplace operator to <code>l</code> and
<code>object(r)</code>, respectively.</dt>
<dt><b>Returns:</b> <code>l</code>.</dt>
</dl>
<pre>
inline long len(object const&amp; obj);
</pre>
<dl class="function-semantics">
<dt><b>Effects:</b> PyObject_Length(obj.ptr()) </dt>
<dt><b>Returns:</b> len() of object.</dt>
</dl>
<h2><a name="examples"></a>Example</h2>
Python code:
<pre>
def sum_items(seq):
result = 0
for x in seq:
result += x
return result
</pre>
C++ version:
<pre>
object sum_items(object seq)
{
object result = object(0);
for (int i = 0; i &lt; len(seq); ++i)
result += seq[i];
return result;
}
</pre>
<p>Revised
<!--webbot bot="Timestamp" S-Type="EDITED" S-Format="%d %B, %Y" startspan -->
15 March, 2010
<!--webbot bot="Timestamp" endspan i-checksum="39359" -->
</p>
<p><i>&copy; Copyright <a href=
"http://www.boost.org/people/dave_abrahams.htm">Dave Abrahams</a> 2008.</i></p>
</body>
</html>