<!-- ##### SECTION Title ##### -->
Types

<!-- ##### SECTION Short_Description ##### -->
Handle run-time type creation

<!-- ##### SECTION Long_Description ##### -->
<para>
The GTK+ type system is extensible.  Because of that, types have to be
managed at runtime.
</para>

<!-- ##### SECTION See_Also ##### -->
<para>

</para>

<!-- ##### TYPEDEF GtkType ##### -->
<para>
#GtkType is unique integer identifying the type.  The guts of the
information about the type is held in a private struct named
#GtkTypeNode.
</para>


<!-- ##### TYPEDEF GtkFundamentalType ##### -->
<para>
#GtkFundamentalType is an enumerated type which lists all the possible
fundamental types (e.g. <type>char</type>, <type>uchar</type>, <type>int</type>,
<type>long</type>, <type>float</type>, etc).
</para>


<!-- ##### MACRO GTK_CLASS_NAME ##### -->
<para>
Returns the type name of @class.
</para>

@class: a #GtkTypeClass.


<!-- ##### MACRO GTK_CLASS_TYPE ##### -->
<para>
Returns the type of @class.
</para>

@class: a #GtkTypeClass.


<!-- ##### MACRO GTK_TYPE_IS_OBJECT ##### -->
<para>
Returns %TRUE if @type is a %GTK_TYPE_OBJECT.
</para>

@type: a #GtkType.


<!-- ##### MACRO GTK_TYPE_FUNDAMENTAL_LAST ##### -->
<para>
The highest-numbered structured or flat enumerated type value.
</para>



<!-- ##### MACRO GTK_TYPE_FUNDAMENTAL_MAX ##### -->
<para>
The maximum fundamental enumerated type value.
</para>



<!-- ##### MACRO GTK_STRUCT_OFFSET ##### -->
<para>
Use in place of <function>offsetof()</function>, which is used if it exists.
</para>

<!-- # Unused Parameters # -->
@struct: The type of the structure.
@field: The field within the structure.


<!-- ##### MACRO GTK_CHECK_CAST ##### -->
<para>
Casts the object in @tobj into @cast.  If %G_DISABLE_CAST_CHECKS is
defined, just cast it.  Otherwise, check to see if we can cast @tobj
into a @cast.
</para>

<!-- # Unused Parameters # -->
@tobj: a #GtkObject.
@cast_type: a GTK+ type.
@cast: a C type


<!-- ##### MACRO GTK_CHECK_CLASS_CAST ##### -->
<para>
Casts the object in @tobj into @cast.  If %G_DISABLE_CAST_CHECKS is
defined, just cast it.  Otherwise, check to see if we can cast @tobj
into a @cast.
</para>

<!-- # Unused Parameters # -->
@tclass: a #GtkClassInitFunc
@cast_type: a GTK+ type.
@cast: a C type


<!-- ##### MACRO GTK_CHECK_TYPE ##### -->
<para>
Determines whether @type_object is a type of @otype.
</para>

<!-- # Unused Parameters # -->
@type_object: a #GtkTypeObject object
@otype: 


<!-- ##### MACRO GTK_CHECK_CLASS_TYPE ##### -->
<para>
Determines whether @type_class is a type of @otype.
</para>

<!-- # Unused Parameters # -->
@type_class: a #GtkTypeClass class.
@otype: 


<!-- ##### MACRO GTK_CHECK_GET_CLASS ##### -->
<para>
Gets the class of @tobj.
</para>

<!-- # Unused Parameters # -->
@tobj: a #GtkObject.


<!-- ##### MACRO GTK_FUNDAMENTAL_TYPE ##### -->
<para>
Converts a GTK+ type into a fundamental type.
</para>

<!-- # Unused Parameters # -->
@type: 


<!-- ##### MACRO GTK_SIGNAL_FUNC ##### -->
<para>
Just a macroized cast into a #GtkSignalFunc.
</para>

@f: 


<!-- ##### TYPEDEF GtkClassInitFunc ##### -->
<para>
Defines a function pointer.
</para>


<!-- ##### TYPEDEF GtkObjectInitFunc ##### -->
<para>
Defines a function pointer.
</para>


<!-- ##### USER_FUNCTION GtkSignalFunc ##### -->
<para>
Defines a function pointer.
</para>



<!-- ##### USER_FUNCTION GtkFunction ##### -->
<para>
Defines a function pointer.
</para>

@data: #gpointer
@Returns: #gint


<!-- ##### USER_FUNCTION GtkDestroyNotify ##### -->
<para>
Defines a function pointer.
</para>

@data: #gpointer


<!-- ##### USER_FUNCTION GtkCallbackMarshal ##### -->
<para>
Defines a function pointer.
</para>

@object: #GtkObject*
@data: #gpointer
@n_args: #guint
@args: #GtkArg*


<!-- ##### TYPEDEF GtkSignalMarshaller ##### -->
<para>
Defines a function pointer.
</para>


<!-- ##### TYPEDEF GtkTypeObject ##### -->
<para>
A #GtkTypeObject defines the minimum structure requirements
for type instances. Type instances returned from gtk_type_new ()
and initialized through a #GtkObjectInitFunc need to directly inherit
from this structure or at least copy its fields one by one.
</para>


<!-- ##### STRUCT GtkArg ##### -->
<para>
This is a structure that we use to pass in typed values (and names).
</para>

@type: 
@name: 

<!-- ##### MACRO GTK_VALUE_CHAR ##### -->
<para>
Gets the value of a #GtkArg whose #GtkType is %GTK_TYPE_CHAR.
</para>

@a: a #GtkArg.


<!-- ##### MACRO GTK_VALUE_UCHAR ##### -->
<para>
Gets the value of a #GtkArg whose #GtkType is %GTK_TYPE_UCHAR.
</para>

@a: a #GtkArg.


<!-- ##### MACRO GTK_VALUE_BOOL ##### -->
<para>
Gets the value of a #GtkArg whose #GtkType is %GTK_TYPE_BOOL.
</para>

@a: a #GtkArg.


<!-- ##### MACRO GTK_VALUE_INT ##### -->
<para>
Gets the value of a #GtkArg whose #GtkType is %GTK_TYPE_INT.
</para>

@a: a #GtkArg.


<!-- ##### MACRO GTK_VALUE_UINT ##### -->
<para>
Gets the value of a #GtkArg whose #GtkType is %GTK_TYPE_UINT.
</para>

@a: a #GtkArg.


<!-- ##### MACRO GTK_VALUE_LONG ##### -->
<para>
Gets the value of a #GtkArg whose #GtkType is %GTK_TYPE_LONG.
</para>

@a: a #GtkArg.


<!-- ##### MACRO GTK_VALUE_ULONG ##### -->
<para>
Gets the value of a #GtkArg whose #GtkType is %GTK_TYPE_ULONG.
</para>

@a: a #GtkArg.


<!-- ##### MACRO GTK_VALUE_FLOAT ##### -->
<para>
Gets the value of a #GtkArg whose #GtkType is %GTK_TYPE_FLOAT.
</para>

@a: a #GtkArg.


<!-- ##### MACRO GTK_VALUE_DOUBLE ##### -->
<para>
Gets the value of a #GtkArg whose #GtkType is %GTK_TYPE_DOUBLE.
</para>

@a: a #GtkArg.


<!-- ##### MACRO GTK_VALUE_STRING ##### -->
<para>
Gets the value of a #GtkArg whose #GtkType is %GTK_TYPE_STRING.
</para>

@a: a #GtkArg.


<!-- ##### MACRO GTK_VALUE_ENUM ##### -->
<para>
Gets the value of a #GtkArg whose #GtkType is %GTK_TYPE_ENUM.
</para>

@a: a #GtkArg.


<!-- ##### MACRO GTK_VALUE_FLAGS ##### -->
<para>
Gets the value of a #GtkArg whose #GtkType is %GTK_TYPE_FLAGS.
</para>

@a: a #GtkArg.


<!-- ##### MACRO GTK_VALUE_BOXED ##### -->
<para>
Gets the value of a #GtkArg whose #GtkType is %GTK_TYPE_BOXED.
</para>

@a: a #GtkArg.


<!-- ##### MACRO GTK_VALUE_POINTER ##### -->
<para>
Gets the value of a #GtkArg whose #GtkType is %GTK_TYPE_POINTER.
</para>

@a: a #GtkArg.


<!-- ##### MACRO GTK_VALUE_OBJECT ##### -->
<para>
Gets the value of a #GtkArg whose #GtkType is %GTK_TYPE_OBJECT.
</para>

@a: a #GtkArg.


<!-- ##### MACRO GTK_VALUE_SIGNAL ##### -->
<para>
Gets the value of a #GtkArg whose #GtkType is %GTK_TYPE_SIGNAL.
</para>

@a: a #GtkArg.


<!-- ##### MACRO GTK_RETLOC_CHAR ##### -->
<para>
If the #GtkArg contains a pointer to the value, this macro will be a pointer to a %GTK_TYPE_CHAR.
</para>

@a: a #GtkArg.


<!-- ##### MACRO GTK_RETLOC_UCHAR ##### -->
<para>
If the #GtkArg contains a pointer to the value, this macro will be a pointer to a %GTK_TYPE_UCHAR.
</para>

@a: a #GtkArg.


<!-- ##### MACRO GTK_RETLOC_BOOL ##### -->
<para>
If the #GtkArg contains a pointer to the value, this macro will be a pointer to a %GTK_TYPE_BOOL.
</para>

@a: a #GtkArg.


<!-- ##### MACRO GTK_RETLOC_INT ##### -->
<para>
If the #GtkArg contains a pointer to the value, this macro will be a pointer to a %GTK_TYPE_INT.
</para>

@a: a #GtkArg.


<!-- ##### MACRO GTK_RETLOC_UINT ##### -->
<para>
If the #GtkArg contains a pointer to the value, this macro will be a pointer to a %GTK_TYPE_UINT.
</para>

@a: a #GtkArg.


<!-- ##### MACRO GTK_RETLOC_LONG ##### -->
<para>
If the #GtkArg contains a pointer to the value, this macro will be a pointer to a %GTK_TYPE_LONG.
</para>

@a: a #GtkArg.


<!-- ##### MACRO GTK_RETLOC_ULONG ##### -->
<para>
If the #GtkArg contains a pointer to the value, this macro will be a pointer to a %GTK_TYPE_ULONG.
</para>

@a: a #GtkArg.


<!-- ##### MACRO GTK_RETLOC_FLOAT ##### -->
<para>
If the #GtkArg contains a pointer to the value, this macro will be a pointer to a %GTK_TYPE_FLOAT.
</para>

@a: a #GtkArg.


<!-- ##### MACRO GTK_RETLOC_DOUBLE ##### -->
<para>
If the #GtkArg contains a pointer to the value, this macro will be a pointer to a %GTK_TYPE_DOUBLE.
</para>

@a: a #GtkArg.


<!-- ##### MACRO GTK_RETLOC_STRING ##### -->
<para>
If the #GtkArg contains a pointer to the value, this macro will be a pointer to a %GTK_TYPE_STRING.
</para>

@a: a #GtkArg.


<!-- ##### MACRO GTK_RETLOC_ENUM ##### -->
<para>
If the #GtkArg contains a pointer to the value, this macro will be a pointer to a %GTK_TYPE_ENUM.
</para>

@a: a #GtkArg.


<!-- ##### MACRO GTK_RETLOC_FLAGS ##### -->
<para>
If the #GtkArg contains a pointer to the value, this macro will be a pointer to a %GTK_TYPE_FLAGS.
</para>

@a: a #GtkArg.


<!-- ##### MACRO GTK_RETLOC_BOXED ##### -->
<para>
If the #GtkArg contains a pointer to the value, this macro will be a pointer to a %GTK_TYPE_BOXED.
</para>

@a: a #GtkArg.


<!-- ##### MACRO GTK_RETLOC_POINTER ##### -->
<para>
If the #GtkArg contains a pointer to the value, this macro will be a pointer to a %GTK_TYPE_POINTER.
</para>

@a: a #GtkArg.


<!-- ##### MACRO GTK_RETLOC_OBJECT ##### -->
<para>
If the #GtkArg contains a pointer to the value, this macro will be a pointer to a %GTK_TYPE_OBJECT.
</para>

@a: a #GtkArg.


<!-- ##### STRUCT GtkTypeInfo ##### -->
<para>
Holds information about the type.  gtk_type_name() returns the name.
@object_size is somehow set to the number of bytes that an instance of
the object will occupy.  @class_init_func holds the type's
initialization function.  @object_init_func holds the initialization
function for an instance of the object.  @reserved_1 is used for
#GtkEnumValue to hold the enumerated values.
</para>

@type_name: 
@object_size: 
@class_size: 
@class_init_func: 
@object_init_func: 
@reserved_1: 
@reserved_2: 
@base_class_init_func: 

<!-- ##### TYPEDEF GtkTypeClass ##### -->
<para>
The base structure for a GTK+ type. Every type inherits this as a base structure.
</para>


<!-- ##### TYPEDEF GtkEnumValue ##### -->
<para>
A structure which contains a single enum value, and its name, and it's
nickname.
</para>


<!-- ##### TYPEDEF GtkFlagValue ##### -->
<para>

</para>


<!-- ##### FUNCTION gtk_type_init ##### -->
<para>
Initializes the data structures associated with GTK+ types.
</para>

@debug_flags: 


<!-- ##### FUNCTION gtk_type_unique ##### -->
<para>
Creates a new, unique type.
</para>

@parent_type: if zero, a fundamental type is created.
@gtkinfo: 
@Returns: the new #GtkType.
<!-- # Unused Parameters # -->
@type_info: must not be %NULL, and @type_info->type_name must also not be %NULL.


<!-- ##### MACRO gtk_type_name ##### -->
<para>
Returns a pointer to the name of a type, or %NULL if it has none.
</para>

@type: a #GtkType.
@Returns: a pointer to the name of a type, or %NULL if it has none.


<!-- ##### MACRO gtk_type_from_name ##### -->
<para>
Gets the internal representation of a type, given its name.
</para>

@name: the name of a GTK+ type
@Returns: a #GtkType.


<!-- ##### MACRO gtk_type_parent ##### -->
<para>
Returns the parent type of a #GtkType.
</para>

@type: a #GtkType.
@Returns: the #GtkType of the parent.


<!-- ##### FUNCTION gtk_type_class ##### -->
<para>
Returns a pointer pointing to the class of @type or %NULL if there was
any trouble identifying @type.  Initializes the class if necessary.
</para>

@type: a #GtkType.
@Returns: pointer to the class.


<!-- ##### FUNCTION gtk_type_new ##### -->
<para>
Creates a new object of a given type, and return a pointer to it.
Returns %NULL if you give it an invalid type.  It allocates the object
out of the type's memory chunk if there is a memory chunk.  The object
has all the proper initializers called.
</para>

@type: a #GtkType.
@Returns: pointer to a #GtkTypeObject.


<!-- ##### MACRO gtk_type_is_a ##### -->
<para>
Looks in the type hierarchy to see if @type has @is_a_type among its
ancestors.  Do so with a simple lookup, not a loop.
</para>

@type: a #GtkType.
@is_a_type: another #GtkType.
@Returns: %TRUE if @type is a @is_a_type.


<!-- ##### FUNCTION gtk_type_enum_get_values ##### -->
<para>
If @enum_type has values, then return a pointer to all of them.
</para>

@enum_type: a #GtkType.
@Returns: #GtkEnumValue*


<!-- ##### FUNCTION gtk_type_flags_get_values ##### -->
<para>
If @flags_type has values, then return a pointer to all of them.
</para>

@flags_type: a #GtkType.
@Returns: #GtkFlagValue*


<!-- ##### FUNCTION gtk_type_enum_find_value ##### -->
<para>
Returns a pointer to one of @enum_type's #GtkEnumValues's whose name (or nickname) matches @value_name.
</para>

@enum_type: a #GtkType.
@value_name: the name to look for.
@Returns: #GtkEnumValue*


<!-- ##### FUNCTION gtk_type_flags_find_value ##### -->
<para>
Returns a pointer to one of @flag_type's #GtkFlagValue's whose name (or nickname) matches @value_name.
</para>

@flags_type: a #GtkType.
@value_name: the name to look for.
@Returns: #GtkFlagValue*
<!-- # Unused Parameters # -->
@flag_type: GtkType


