gtype.sgml

GLib是GTK+和GNOME工程的基础底层核心程序库

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<title><anchor id="g-type-init-with-debug-flags">g_type_init_with_debug_flags ()</title>
<programlisting>void        g_type_init_with_debug_flags    (<link linkend="GTypeDebugFlags">GTypeDebugFlags</link> debug_flags);</programlisting>
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<row><entry align="right"><parameter>debug_flags</parameter>&nbsp;:</entry>
<entry>


</entry></row>
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<title><anchor id="g-type-name">g_type_name ()</title>
<programlisting>G_CONST_RETURN <link linkend="gchar">gchar</link>* g_type_name           (<link linkend="GType">GType</link> type);</programlisting>
<para>
Return the unique name that is assigned to a type ID (this is the preferred method
to find out whether a specific type has been registered for the passed in ID yet).
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<row><entry align="right"><parameter>type</parameter>&nbsp;:</entry>
<entry>		Type to return name for.
</entry></row>
<row><entry align="right"><emphasis>Returns</emphasis> :</entry><entry>	Static type name or NULL.


</entry></row>
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<title><anchor id="g-type-qname">g_type_qname ()</title>
<programlisting><link linkend="GQuark">GQuark</link>      g_type_qname                    (<link linkend="GType">GType</link> type);</programlisting>
<para>
Return the corresponding quark of the type IDs name.
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<row><entry align="right"><parameter>type</parameter>&nbsp;:</entry>
<entry>   Type to return quark of type name for.
</entry></row>
<row><entry align="right"><emphasis>Returns</emphasis> :</entry><entry>The type names quark or 0.


</entry></row>
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<refsect2>
<title><anchor id="g-type-from-name">g_type_from_name ()</title>
<programlisting><link linkend="GType">GType</link>       g_type_from_name                (const <link linkend="gchar">gchar</link> *name);</programlisting>
<para>
Lookup the type ID from a given type name, returns 0 if no type has been registered under this name
(this is the preferred method to find out by name whether a specific type has been registered yet).
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<row><entry align="right"><parameter>name</parameter>&nbsp;:</entry>
<entry>   Type name to lookup.
</entry></row>
<row><entry align="right"><emphasis>Returns</emphasis> :</entry><entry>Corresponding type ID or 0.


</entry></row>
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<title><anchor id="g-type-parent">g_type_parent ()</title>
<programlisting><link linkend="GType">GType</link>       g_type_parent                   (<link linkend="GType">GType</link> type);</programlisting>
<para>
Return the direct parent type of the passed in type.
If the passed in type has no parent, i.e. is a fundamental type, 0 is returned.
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<row><entry align="right"><parameter>type</parameter>&nbsp;:</entry>
<entry>   The derived type.
</entry></row>
<row><entry align="right"><emphasis>Returns</emphasis> :</entry><entry>The parent type.


</entry></row>
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<title><anchor id="g-type-depth">g_type_depth ()</title>
<programlisting><link linkend="guint">guint</link>       g_type_depth                    (<link linkend="GType">GType</link> type);</programlisting>
<para>

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<row><entry align="right"><parameter>type</parameter>&nbsp;:</entry>
<entry>
</entry></row>
<row><entry align="right"><emphasis>Returns</emphasis> :</entry><entry>


</entry></row>
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<refsect2>
<title><anchor id="g-type-next-base">g_type_next_base ()</title>
<programlisting><link linkend="GType">GType</link>       g_type_next_base                (<link linkend="GType">GType</link> leaf_type,
                                             <link linkend="GType">GType</link> root_type);</programlisting>
<para>
Given a <parameter>leaf_type</parameter> and a <parameter>root_type</parameter> which is contained in its anchestry, return
the type that <parameter>root_type</parameter> is the immediate parent of.
In other words, this function determines the type that is derived directly from
<parameter>root_type</parameter> which is also a base class of <parameter>leaf_type</parameter>.  Given a root type and a
leaf type, this function can be used to determine the types and order in which
the leaf type is descended from the root type.
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<row><entry align="right"><parameter>leaf_type</parameter>&nbsp;:</entry>
<entry>	Descendant of <parameter>root_type</parameter> and the type to be returned.
</entry></row>
<row><entry align="right"><parameter>root_type</parameter>&nbsp;:</entry>
<entry>	Immediate parent of the returned type.
</entry></row>
<row><entry align="right"><emphasis>Returns</emphasis> :</entry><entry>	Immediate child of <parameter>root_type</parameter> and anchestor of <parameter>leaf_type</parameter>.


</entry></row>
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<title><anchor id="g-type-is-a">g_type_is_a ()</title>
<programlisting><link linkend="gboolean">gboolean</link>    g_type_is_a                     (<link linkend="GType">GType</link> type,
                                             <link linkend="GType">GType</link> is_a_type);</programlisting>
<para>
Check whether <parameter>type</parameter> is a descendant of <parameter>is_a_type</parameter>.
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<row><entry align="right"><parameter>type</parameter>&nbsp;:</entry>
<entry>     Type to check anchestry for.
</entry></row>
<row><entry align="right"><parameter>is_a_type</parameter>&nbsp;:</entry>
<entry>Possible anchestor of <parameter>type</parameter>.
</entry></row>
<row><entry align="right"><emphasis>Returns</emphasis> :</entry><entry>  <literal>TRUE</literal> if <parameter>type</parameter> is_a <parameter>is_a_type</parameter> holds true.


</entry></row>
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<title><anchor id="g-type-class-ref">g_type_class_ref ()</title>
<programlisting><link linkend="gpointer">gpointer</link>    g_type_class_ref                (<link linkend="GType">GType</link> type);</programlisting>
<para>
Increments the reference count of the class structure belonging to
<parameter>type</parameter>. This function will demand-create the class if it doesn't
exist already.
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<row><entry align="right"><parameter>type</parameter>&nbsp;:</entry>
<entry>	  Type ID of a classed type.
</entry></row>
<row><entry align="right"><emphasis>Returns</emphasis> :</entry><entry>The <link linkend="GTypeClass">GTypeClass</link> structure for the given type ID.


</entry></row>
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<title><anchor id="g-type-class-peek">g_type_class_peek ()</title>
<programlisting><link linkend="gpointer">gpointer</link>    g_type_class_peek               (<link linkend="GType">GType</link> type);</programlisting>
<para>
This function is essentially the same as <link linkend="g-type-class-ref">g_type_class_ref</link>(), except that
the classes reference count isn't incremented. Therefore, this function
may return NULL if the class of the type passed in does not currently
exist (hasn't been referenced before).
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<row><entry align="right"><parameter>type</parameter>&nbsp;:</entry>
<entry>		Type ID of a classed type.
</entry></row>
<row><entry align="right"><emphasis>Returns</emphasis> :</entry><entry>	The <link linkend="GTypeClass">GTypeClass</link> structure for the given type ID or NULL
		if the class does not currently exist.


</entry></row>
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<title><anchor id="g-type-class-unref">g_type_class_unref ()</title>
<programlisting>void        g_type_class_unref              (<link linkend="gpointer">gpointer</link> g_class);</programlisting>
<para>
Decrements the reference count of the class structure being passed in.
Once the last reference count of a class has been released, classes
may be finalized by the type system, so further dereferencing of a
class pointer after <link linkend="g-type-class-unref">g_type_class_unref</link>() are invalid.
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<row><entry align="right"><parameter>g_class</parameter>&nbsp;:</entry>
<entry>	The <link linkend="GTypeClass">GTypeClass</link> structure to unreference.


</entry></row>
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<title><anchor id="g-type-class-peek-parent">g_type_class_peek_parent ()</title>
<programlisting><link linkend="gpointer">gpointer</link>    g_type_class_peek_parent        (<link linkend="gpointer">gpointer</link> g_class);</programlisting>
<para>
This is a convenience function, often needed in class intializers.
It essentially takes the immediate parent type of the class passed in,
and returns the class structure thereof. Since derived classes hold
a reference count on their parent classes as long as they are instantiated,
the returned class will always exist. This function is essentially
equivalent to:

<msgtext><programlisting>
g_type_class_peek (g_type_parent (G_TYPE_FROM_CLASS (g_class)));
</programlisting></msgtext>

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<row><entry align="right"><parameter>g_class</parameter>&nbsp;:</entry>
<entry>The <link linkend="GTypeClass">GTypeClass</link> structure to retrieve the parent class for.
</entry></row>
<row><entry align="right"><emphasis>Returns</emphasis> :</entry><entry>The parent class of <parameter>g_class</parameter>.


</entry></row>
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<title><anchor id="g-type-interface-peek">g_type_interface_peek ()</title>
<programlisting><link linkend="gpointer">gpointer</link>    g_type_interface_peek           (<link linkend="gpointer">gpointer</link> instance_class,
                                             <link linkend="GType">GType</link> iface_type);</programlisting>
<para>

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<row><entry align="right"><parameter>instance_class</parameter>&nbsp;:</entry>
<entry>
</entry></row>
<row><entry align="right"><parameter>iface_type</parameter>&nbsp;:</entry>
<entry>
</entry></row>
<row><entry align="right"><emphasis>Returns</emphasis> :</entry><entry>


</entry></row>
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<title><anchor id="g-type-interface-peek-parent">g_type_interface_peek_parent ()</title>
<programlisting><link linkend="gpointer">gpointer</link>    g_type_interface_peek_parent    (<link linkend="gpoi