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<?xml version="1.0" standalone="no"?>
<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
    "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd">

  <chapter id="pygobject-introduction">
  <title>Introduction</title>

  <para>This document describes many of the <literal>PyGObject</literal>
  version 2.12 classes and their methods and associated
  functions. Deprecated classes, functions and methods have been
  specifically left out of this reference though classes that have become
  deprecated since PyGObject 2.0 have been left in but annotated with a
  deprecation warning. This document attempts to document as much of the
  <literal>PyGObject</literal> <literal>API</literal> as possible but there
  are undoubtedly errors and omissions. If you discover any of these please
  file a bug report at <ulink
  url="http://bugzilla.gnome.org">bugzilla.gnome.org</ulink> for the
  <literal>pygobject</literal> project. Specific areas that have not been
  documented include:</para>

  <itemizedlist>
    <listitem>
      <simpara>The GParamSpec class</simpara>
    </listitem>
  </itemizedlist>

  <para>This reference describes the API for <literal>PyGObject</literal> as
  of version 2.11.0+ and assumes that the additional API changes for version
  2.12 will not be significant. There will undoubtedly be changes that are
  not reflected in this reference. The differences in the API between
  version 2.0 and previous versions are denoted in this reference with a
  Note that describes the availability of the object, constructor, method or
  function. Any of these that do not have a notation can be assumed to be
  available in all versions of PyGObject from 2.0 and up. The source code
  must be consulted if this reference and your version of
  <literal>PyGObject</literal> seem to differ. You are encouraged to use the
  latest version of <literal>PyGObject</literal> that is available. See the
  <ulink url="http://www.pygtk.org"><literal>PyGTK</literal>
  homepage</ulink> for more information and more resources on how to use
  PyGObject as well as help in its development.</para>

  <para> The Reference contains a chapter for each
  <literal>PyGObject</literal> module containing the class descriptions. The
  class descriptions are arranged alphabetically within the
  chapters. Currently there is one module chapter:</para>

  <variablelist>
    <varlistentry>
      <term>The&nbsp;<literal>gobject</literal>&nbsp;module</term>
      <listitem><simpara>The classes that are included in the
<literal>gobject</literal> module of <literal>PyGObject</literal> and are
accessed similar to: gobject.GObject. These classes are the base object
classes that the <literal>gtk</literal> and <literal>gtk.gdk</literal>
module classes are built on.</simpara>
      </listitem>
    </varlistentry>
  </variablelist>

<!--
  <sect1>
    <title>Major Changes since Version 2.11</title>

    <para>The major changes in this document since version 2.11
    include:</para>

    <itemizedlist>
      <listitem>
	<para></para>
      </listitem>
    </itemizedlist>

  </sect1>
-->

  <sect1 id="pygobject-reference-format">
    <title>Reference Page Format</title>

    <para>Each <literal>PyGObject</literal> class is described in a reference
page that has a number of sections in a fixed format. Each reference page
will have a subset of the following sections:</para>

    <variablelist>
      <varlistentry>
	<term>Name</term>
	<listitem>
	  <simpara>The name and a one-line description of the
class.</simpara>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term>Synopsis</term>
	<listitem>
	  <simpara>A synopsis of the class and its methods and
optionally a list of associated functions.</simpara>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term>Ancestry</term>
	<listitem>
	  <simpara>The list of the parent classes of the class. This
section may not be present in all class descriptions.</simpara>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term>Properties</term>
 	<listitem>
	  <simpara>A list of the properties (internal state)
supported by the class. This section may not be present in all classes. The
property descriptions include the name, the access operations (e.g. Read,
Write), and a brief description. Properties are accessed using the <link
linkend="method-gobject--set-property"><methodname>gobject.set_property</methodname>()</link> 
and <link
linkend="method-gobject--get-property"><methodname>gobject.get_property</methodname>()</link> 
methods that are available to every <literal>PyGObject</literal> object. This
section may not be present in all class descriptions.</simpara>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term>Attributes</term>
	<listitem>
	  <simpara>A set of internal object state data accessible as Python
	  attributes (e.g. object.attr). The attribute descriptions include
	  a name by which the attribute data is accessed, the access mode
	  (e.g. Read, Write), and a brief description of the attribute. Most
	  <literal>PyGObject</literal> classes do not support attributes so
	  this section is not present in most class descriptions.</simpara>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term>Signal&nbsp;Prototypes</term>
	<listitem>
	  <simpara>A list of the signals supported by the class including
	  the signal name and a synopsis of the signal handler function
	  prototype. This section may not be present in all class
	  descriptions.</simpara>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term>Description</term>
	<listitem><simpara>A description of the class and possibly some of
	the methods supported by the class.</simpara>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term>Constructor</term>
	<listitem>
	  <simpara>The description of the class object constructor including
	  the synopsis with brief parameter descriptions and a description
	  of th use of the constructor. There may be more than one
	  constructor description if the constructor supports different
	  parameter lists. This section may not be present in all class
	  descriptions.</simpara>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term>Methods</term>
	<listitem>
	  <simpara>A list of methods supported by the class. Each method
	  description includes: a synopsis of the method and its parameters
	  as well as a brief description of each parameter and return value
	  (if any); and, a description of the use of the method.</simpara>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term>Functions</term>
	<listitem>
	  <simpara>A list of related functions. Each function description
	  includes a synopsis of the function and its parameters and return
	  value (if any), and a description of the use of the
	  function.</simpara>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term>Signals</term>
	<listitem>
	  <simpara>A list of signals including a synopsis of the signal
	  handler prototype function with its parameters and return value
	  (if any). The signal emission conditions are briefly
	  described. This section is not present in all class descriptions;
	  specifically, the <literal>gtk.gdk</literal> classes do not
	  usually support signals.</simpara>
	</listitem>
      </varlistentry>
    </variablelist>

    <para>The function and method synopsis parameters are displayed in
    <emphasis role="bold">bold</emphasis> to denote Python keyword
    parameters.  Also if the parameter is optional its default value will be
    displayed. For example the <link
    linkend="function-gobject--signal-lookup"><function>gobject.signal_lookup</function>()</link>
    function synopsis is:</para>

    <programlisting>
<methodsynopsis language="python">
	<methodname><link
linkend="function-gobject--signal-lookup">gobject.signal_lookup</link></methodname>
	<methodparam><parameter
		       role="keyword">name</parameter></methodparam>
	<methodparam><parameter
		       role="keyword">type</parameter></methodparam>
      </methodsynopsis>
</programlisting>

    <para>The parameters <parameter>name</parameter> and
    <parameter>type</parameter> are keyword parameters that can be specified
    in a call either by position or keyword (in which case position is not
    important). The following calls have the same result:</para>

    <programlisting>
  id = gobject.signal_lookup("clicked", gtk.Button)
  id = gobject.signal_lookup("clicked", type=gtk.Button)
  id = gobject.signal_lookup(name="clicked", type=gtk.Button)
  id = gobject.signal_lookup(type=gtk.Button, name="clicked")
</programlisting>

    <para>Parameters that are not keyword parameters are displayed in
<emphasis>italic</emphasis> and must be specified positionally but may also
be optional.</para>

  </sect1>

  </chapter>