GType

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GType

A numerical value which represents the unique identifier of a registered type.

G_TYPE_FUNDAMENTAL()

#define G_TYPE_FUNDAMENTAL(type)	(g_type_fundamental (type))

Returns TRUE if type is a fundamental data type such as G_TYPE_INT or G_TYPE_POINTER. Fundamental types are types that serve as fundaments for the derived types, thus they are the roots of distinct inheritance hierarchies.

type�: A GType value.

G_TYPE_FUNDAMENTAL_MAX

#define	G_TYPE_FUNDAMENTAL_MAX		(255 << G_TYPE_FUNDAMENTAL_SHIFT)

An integer constant that represents the number of identifiers reserved for types that are assigned at compile-time.

G_TYPE_MAKE_FUNDAMENTAL()

#define	G_TYPE_MAKE_FUNDAMENTAL(x)	((GType) ((x) << G_TYPE_FUNDAMENTAL_SHIFT))

Returns the type ID for the fundamental type number x. Use g_type_fundamental_next() instead of this macro to create new fundamental types.

x�: the fundamental type number.

G_TYPE_IS_ABSTRACT()

#define G_TYPE_IS_ABSTRACT(type)                (g_type_test_flags ((type), G_TYPE_FLAG_ABSTRACT))

Returns TRUE if type is an abstract type. An abstract type can not be instantiated and is normally used as an abstract base class for derived classes.

type�: A GType value.

G_TYPE_IS_DERIVED()

#define G_TYPE_IS_DERIVED(type)                 ((type) > G_TYPE_FUNDAMENTAL_MAX)

Returns TRUE if type is derived (or in object-oriented terminology: inherited) from another type (this holds true for all non-fundamental types).

type�: A GType value.

G_TYPE_IS_FUNDAMENTAL()

#define G_TYPE_IS_FUNDAMENTAL(type)             ((type) <= G_TYPE_FUNDAMENTAL_MAX)

Returns TRUE if type is a fundamental type.

type�: A GType value.

G_TYPE_IS_VALUE_TYPE()

#define G_TYPE_IS_VALUE_TYPE(type)              (g_type_check_is_value_type (type))

type�: A GType value.

G_TYPE_HAS_VALUE_TABLE()

#define G_TYPE_HAS_VALUE_TABLE(type)            (g_type_value_table_peek (type) != NULL)

Returns TRUE if type has a GTypeValueTable.

type�: A GType value.

G_TYPE_IS_CLASSED()

#define G_TYPE_IS_CLASSED(type)                 (g_type_test_flags ((type), G_TYPE_FLAG_CLASSED))

Returns TRUE if type is a classed type.

type�: A GType value.

G_TYPE_IS_INSTANTIATABLE()

#define G_TYPE_IS_INSTANTIATABLE(type)          (g_type_test_flags ((type), G_TYPE_FLAG_INSTANTIATABLE))

Returns TRUE if type can be instantiated. Instantiation is the process of creating an instance (object) of this type.

type�: A GType value.

G_TYPE_IS_DERIVABLE()

#define G_TYPE_IS_DERIVABLE(type)               (g_type_test_flags ((type), G_TYPE_FLAG_DERIVABLE))

Returns TRUE if type is a derivable type. A derivable type can be used as the base class of a flat (single-level) class hierarchy.

type�: A GType value.

G_TYPE_IS_DEEP_DERIVABLE()

#define G_TYPE_IS_DEEP_DERIVABLE(type)          (g_type_test_flags ((type), G_TYPE_FLAG_DEEP_DERIVABLE))

Returns TRUE if type is a deep derivable type. A deep derivable type can be used as the base class of a deep (multi-level) class hierarchy.

type�: A GType value.

G_TYPE_IS_INTERFACE()

#define G_TYPE_IS_INTERFACE(type)               (G_TYPE_FUNDAMENTAL (type) == G_TYPE_INTERFACE)

Returns TRUE if type is an interface type. Interface types are types that provide pure APIs, the implementation of which is provided by another type (which is then said to conform to the interface). GLib interfaces are somewhat analogous to Java interfaces and C++ classes containing only pure virtual functions, with the difference that GType interfaces are not derivable (but see g_type_interface_add_prerequisite() for an alternative).

type�: A GType value.

struct GTypeInterface

struct GTypeInterface
{
  /*< private >*/
  GType g_type;         /* iface type */
  GType g_instance_type;
};

An opaque structure used as the base of all interface types.

struct GTypeInstance

struct GTypeInstance
{
  /*< private >*/
  GTypeClass *g_class;
};

An opaque structure used as the base of all type instances.

struct GTypeInfo

struct GTypeInfo
{
  /* interface types, classed types, instantiated types */
  guint16                class_size;
  
  GBaseInitFunc          base_init;
  GBaseFinalizeFunc      base_finalize;
  
  /* classed types, instantiated types */
  GClassInitFunc         class_init;
  GClassFinalizeFunc     class_finalize;
  gconstpointer          class_data;
  
  /* instantiated types */
  guint16                instance_size;
  guint16                n_preallocs;
  GInstanceInitFunc      instance_init;
  
  /* value handling */
  const GTypeValueTable	*value_table;
};

This structure is used to provide the type system with the information required to initialize and destruct (finalize) a type's class and instances thereof. The initialized structure is passed to the g_type_register_static() function (or is copied into the provided GTypeInfo structure in the g_type_plugin_complete_type_info()). The type system will perform a deep copy of this structure, so it's memory does not need to be persistent across invocation of g_type_register_static().

guint16 `class_size`	Size of the class structure (required for interface, classed and instantiatable types).
GBaseInitFunc `base_init`	Location of the base initialization function (optional).
GBaseFinalizeFunc `base_finalize`	Location of the base finalization function (optional).
GClassInitFunc `class_init`	Location of the class initialization function (optional, for classed and instantiatable types only).
GClassFinalizeFunc `class_finalize`	Location of the class finalization function (optional).
gconstpointer `class_data`	User-supplied data passed to the class init/finalize functions.
guint16 `instance_size`	Size of the instance (object) structure (required for instantiatable types only).
guint16 `n_preallocs`	Number of pre-allocated (cached) instances to reserve memory for (0 indicates no caching).
GInstanceInitFunc `instance_init`	Location of the instance initialization function (optional, for instantiatable types only).
const GTypeValueTable *`value_table`	A GTypeValueTable function table for generic handling of GValues of this type (usually only useful for fundamental types).

struct GTypeFundamentalInfo

struct GTypeFundamentalInfo
{
  GTypeFundamentalFlags  type_flags;
};

A structure that provides information to the type system which is used specifically for managing fundamental types.

struct GInterfaceInfo

struct GInterfaceInfo
{
  GInterfaceInitFunc     interface_init;
  GInterfaceFinalizeFunc interface_finalize;
  gpointer               interface_data;
};

A structure that provides information to the type system which is used specifically for managing interface types.

GInterfaceInitFunc `interface_init`	Location of the function that initializes the interface.
GInterfaceFinalizeFunc `interface_finalize`	Location of the function that finalizes the interface.
gpointer `interface_data`	Location of user data passed to the `interface_init` and `interface_finalize` functions (optional).

struct GTypeValueTable

struct GTypeValueTable
{
  void     (*value_init)         (GValue       *value);
  void     (*value_free)         (GValue       *value);
  void     (*value_copy)         (const GValue *src_value,
				  GValue       *dest_value);
  /* varargs functionality (optional) */
  gpointer (*value_peek_pointer) (const GValue *value);
  gchar	    *collect_format;
  gchar*   (*collect_value)      (GValue       *value,
				  guint         n_collect_values,
				  GTypeCValue  *collect_values,
				  guint		collect_flags);
  gchar	    *lcopy_format;
  gchar*   (*lcopy_value)        (const GValue *value,
				  guint         n_collect_values,
				  GTypeCValue  *collect_values,
				  guint		collect_flags);
};

The GTypeValueTable provides the functions required by the GValue implementation, to serve as a container for values of a type.

void (*value_init) (GValue *value)

Default initialize values contents by poking values directly into the value->data array. The data array of the GValue passed into this function was zero-filled with memset(), so no care has to be taken to free any old contents. E.g. for the implementation of a string value that may never be NULL, the implementation might look like:

{
  value->data[0].v_pointer = g_strdup ("");
}

void (*value_free) (GValue *value)

Free any old contents that might be left in the data array of the passed in value. No resources may remain allocated through the GValue contents after this function returns. E.g. for our above string type:

{
  /* only free strings without a specific flag for static storage */
  if (!(value->data[1].v_uint & G_VALUE_NOCOPY_CONTENTS))
    g_free (value->data[0].v_pointer);
}

void (*value_copy) (const GValue *src_value, GValue *dest_value)

dest_value is a GValue with zero-filled data section and src_value is a properly setup GValue of same or derived type. The purpose of this function is to copy the contents of src_value into dest_value in a way, that even after src_value has been freed, the contents of dest_value remain valid. String type example:

{
  dest_value->data[0].v_pointer = g_strdup (src_value->data[0].v_pointer);
}

gpointer (*value_peek_pointer) (const GValue *value)

If the value contents fit into a pointer, such as objects or strings, return this pointer, so the caller can peek at the current contents. To extend on our above string example:

{
  return value->data[0].v_pointer;
}

gchar *collect_format

A string format describing how to collect the contents of this value, bit-by-bit. Each character in the format represents an argument to be collected, the characters themselves indicate the type of the argument. Currently supported arguments are:

: 'i' - Integers. passed as collect_values[].v_int.
: 'l' - Longs. passed as collect_values[].v_long.
: 'd' - Doubles. passed as collect_values[].v_double.
: 'p' - Pointers. passed as collect_values[].v_pointer.

It should be noted, that for variable argument list construction, ANSI C promotes every type smaller than an integer to an int, and floats to doubles. So for collection of short int or char, 'i' needs to be used, and for collection of floats 'd'.

gchar* (*collect_value) (GValue *value, guint n_collect_values, GTypeCValue *collect_values, guint collect_flags)

The collect_value() function is responsible for converting the values collected from a variable argument list into contents suitable for storage in a GValue. This function should setup value similar to value_init(), e.g. for a string value that does not allow NULL pointers, it needs to either spew an error, or do an implicit conversion by storing an empty string. The value passed in to this function has a zero-filled data array, so just like for value_init() it is guaranteed to not contain any old contents that might need freeing. n_collect_values is exactly the string length of collect_format, and collect_values is an array of unions GTypeCValue with length n_collect_values, containing the collected values according to collect_format. collect_flags is an argument provided as a hint by the caller, which may contain the flag G_VALUE_NOCOPY_CONTENTS indicating, that the collected value contents may be considered "static" for the duration of the value lifetime. Thus an extra copy of the contents stored in collect_values is not required for assignment to value. For our above string example, we continue with:

{
  if (!collect_values[0].v_pointer)
    value->data[0].v_pointer = g_strdup ("");
  else if (collect_flags & G_VALUE_NOCOPY_CONTENTS)
    {
      value->data[0].v_pointer = collect_values[0].v_pointer;
      /* keep a flag for the value_free() implementation to not free this string */
      value->data[1].v_uint = G_VALUE_NOCOPY_CONTENTS;
    }
  else
    value->data[0].v_pointer = g_strdup (collect_values[0].v_pointer);

  return NULL;
}

It should be noted, that it is generally a bad idea to follow the G_VALUE_NOCOPY_CONTENTS hint for reference counted types. Due to reentrancy requirements and reference count assertions performed by the GSignal code, reference counts should always be incremented for reference counted contents stored in the value->data array. To deviate from our string example for a moment, and taking a look at an exemplary implementation for collect_value() of GObject:

{
  if (collect_values[0].v_pointer)
    {
      GObject *object = G_OBJECT (collect_values[0].v_pointer);

      /* never honour G_VALUE_NOCOPY_CONTENTS for ref-counted types */
      value->data[0].v_pointer = g_object_ref (object);
      return NULL;
    }
  else
    return g_strdup_printf ("Object passed as invalid NULL pointer");
}

The reference count for valid objects is always incremented, regardless of collect_flags. For invalid objects, the example returns a newly allocated string without altering value. Upon success, collect_value() needs to return NULL, if however a malicious condition occurred, collect_value() may spew an error by returning a newly allocated non-NULL string, giving a suitable description of the error condition. The calling code makes no assumptions about the value contents being valid upon error returns, value is simply thrown away without further freeing. As such, it is a good idea to not allocate GValue contents, prior to returning an error, however, collect_values() is not obliged to return a correctly setup value for error returns, simply because any non-NULL return is considered a fatal condition so further program behaviour is undefined.

gchar *lcopy_format Format description of the arguments to collect for lcopy_value, analogous to collect_format. Usually, lcopy_format string consists only of 'p's to provide lcopy_value() with pointers to storage locations.

gchar* (*lcopy_value) (const GValue *value, guint n_collect_values, GTypeCValue *collect_values, guint collect_flags)

This function is responsible for storing the value contents into arguments passed through a variable argument list which got collected into collect_values according to lcopy_format. n_collect_values equals the string length of lcopy_format, and collect_flags may contain G_VALUE_NOCOPY_CONTENTS. In contrast to collect_value(), lcopy_value() is obliged to always properly support G_VALUE_NOCOPY_CONTENTS. Similar to collect_value() the function may prematurely abort by returning a newly allocated string describing an error condition. To complete the string example:

{
  gchar **string_p = collect_values[0].v_pointer;

  if (!string_p)
    return g_strdup_printf ("string location passed as NULL");

  if (collect_flags & G_VALUE_NOCOPY_CONTENTS)
    *string_p = value->data[0].v_pointer;
  else
    *string_p = g_strdup (value->data[0].v_pointer);

}

And an exemplary version of lcopy_value() for reference-counted types:

{
  GObject **object_p = collect_values[0].v_pointer;

  if (!object_p)
    return g_strdup_printf ("object location passed as NULL");
  if (!value->data[0].v_pointer)
    *object_p = NULL;
  else if (collect_flags & G_VALUE_NOCOPY_CONTENTS) /* always honour */
    *object_p = value->data[0].v_pointer;
  else
    *object_p = g_object_ref (value->data[0].v_pointer);
  return NULL;
}

G_TYPE_FROM_INSTANCE()

#define G_TYPE_FROM_INSTANCE(instance)                          (G_TYPE_FROM_CLASS (((GTypeInstance*) (instance))->g_class))

Returns the type identifier from a given instance structure.

instance�: Location of a valid GTypeInstance structure.

G_TYPE_FROM_CLASS()

#define G_TYPE_FROM_CLASS(g_class)                              (((GTypeClass*) (g_class))->g_type)

Returns the type identifier from a given class structure.

g_class�: Location of a valid GTypeClass structure.

G_TYPE_FROM_INTERFACE()

#define G_TYPE_FROM_INTERFACE(g_iface)                          (((GTypeInterface*) (g_iface))->g_type)

Returns the type identifier from a given interface structure.

g_iface�: Location of a valid GTypeInterface structure.

G_TYPE_INSTANCE_GET_CLASS()

#define G_TYPE_INSTANCE_GET_CLASS(instance, g_type, c_type)     (_G_TYPE_IGC ((instance), (g_type), c_type))

Returns the class structure of a given instance, casted to a specified anchestor type g_type of the instance.

`instance`�:	Location of the GTypeInstance structure.
`g_type`�:	The anchestor type of the class to be returned.
`c_type`�:	The corresponding C type of `g_Type`.

G_TYPE_INSTANCE_GET_INTERFACE()

#define G_TYPE_INSTANCE_GET_INTERFACE(instance, g_type, c_type) (_G_TYPE_IGI ((instance), (g_type), c_type))

`instance`�:
`g_type`�:
`c_type`�:

G_TYPE_CHECK_INSTANCE()

#define G_TYPE_CHECK_INSTANCE(instance)				(_G_TYPE_CHI ((GTypeInstance*) (instance)))

instance�:

G_TYPE_CHECK_INSTANCE_CAST()

#define G_TYPE_CHECK_INSTANCE_CAST(instance, g_type, c_type)    (_G_TYPE_CIC ((instance), (g_type), c_type))

`instance`�:
`g_type`�:
`c_type`�:

G_TYPE_CHECK_INSTANCE_TYPE()

#define G_TYPE_CHECK_INSTANCE_TYPE(instance, g_type)            (_G_TYPE_CIT ((instance), (g_type)))

`instance`�:
`g_type`�:

G_TYPE_CHECK_CLASS_CAST()

#define G_TYPE_CHECK_CLASS_CAST(g_class, g_type, c_type)        (_G_TYPE_CCC ((g_class), (g_type), c_type))

`g_class`�:
`g_type`�:
`c_type`�:

G_TYPE_CHECK_CLASS_TYPE()

#define G_TYPE_CHECK_CLASS_TYPE(g_class, g_type)                (_G_TYPE_CCT ((g_class), (g_type)))

`g_class`�:
`g_type`�:

G_TYPE_CHECK_VALUE()

#define G_TYPE_CHECK_VALUE(value)				(_G_TYPE_CHV ((value)))

value�:

G_TYPE_CHECK_VALUE_TYPE()

#define G_TYPE_CHECK_VALUE_TYPE(value, g_type)			(_G_TYPE_CVH ((value), (g_type)))

`value`�:
`g_type`�:

G_TYPE_FLAG_RESERVED_ID_BIT

#define	G_TYPE_FLAG_RESERVED_ID_BIT	((GType) (1 << 0))

g_type_init ()

void        g_type_init                     (void);

Prior to any use of the type system, g_type_init() has to be called to initialize the type system and assorted other code portions (such as the various fundamental type implementations or the signal system).

enum GTypeDebugFlags

typedef enum	/*< skip >*/
{
  G_TYPE_DEBUG_NONE	= 0,
  G_TYPE_DEBUG_OBJECTS	= 1 << 0,
  G_TYPE_DEBUG_SIGNALS	= 1 << 1,
  G_TYPE_DEBUG_MASK	= 0x03
} GTypeDebugFlags;

The GTypeDebugFlags enumeration values can be passed to g_type_init_with_debug_flags() to trigger debugging messages during runtime. Note that the messages can also be triggered by setting the GOBJECT_DEBUG environment variable to a ':'-separated list of "objects" and "signals".

`G_TYPE_DEBUG_NONE`	Print no messages.
`G_TYPE_DEBUG_OBJECTS`	Print messages about object bookkeeping.
`G_TYPE_DEBUG_SIGNALS`	Print messages about signal emissions.
`G_TYPE_DEBUG_MASK`

g_type_init_with_debug_flags ()

void        g_type_init_with_debug_flags    (GTypeDebugFlags debug_flags);

Similar to g_type_init(), but additionally sets debug flags.

debug_flags�: Bitwise combination of GTypeDebugFlags values for debugging purposes.

g_type_name ()

G_CONST_RETURN gchar* g_type_name           (GType type);

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).

`type`�:	Type to return name for.
Returns :	Static type name or `NULL`.

g_type_qname ()

GQuark      g_type_qname                    (GType type);

Return the corresponding quark of the type IDs name.

`type`�:	Type to return quark of type name for.
Returns :	The type names quark or 0.

g_type_from_name ()

GType       g_type_from_name                (const gchar *name);

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).

`name`�:	Type name to lookup.
Returns :	Corresponding type ID or 0.

g_type_parent ()

GType       g_type_parent                   (GType type);

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.

`type`�:	The derived type.
Returns :	The parent type.

g_type_depth ()

guint       g_type_depth                    (GType type);

Returns the length of the ancestry of the passed in type. This includes the type itself, so that e.g. a fundamental type has depth 1.

`type`�:	A GType value.
Returns :	The depth of `type`.

g_type_next_base ()

GType       g_type_next_base                (GType leaf_type,
                                             GType root_type);

Given a leaf_type and a root_type which is contained in its anchestry, return the type that root_type is the immediate parent of. In other words, this function determines the type that is derived directly from root_type which is also a base class of leaf_type. 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.

`leaf_type`�:	Descendant of `root_type` and the type to be returned.
`root_type`�:	Immediate parent of the returned type.
Returns :	Immediate child of `root_type` and anchestor of `leaf_type`.

g_type_is_a ()

gboolean    g_type_is_a                     (GType type,
                                             GType is_a_type);

If is_a_type is a derivable type, check whether type is a descendant of is_a_type. If is_a_type is an interface, check whether type conforms to it.

`type`�:	Type to check anchestry for.
`is_a_type`�:	Possible anchestor of `type` or interface `type` could conform to.
Returns :	`TRUE` if `type` is_a `is_a_type` holds true.

g_type_class_ref ()

gpointer    g_type_class_ref                (GType type);

Increments the reference count of the class structure belonging to type. This function will demand-create the class if it doesn't exist already.

`type`�:	Type ID of a classed type.
Returns :	The GTypeClass structure for the given type ID.

g_type_class_peek ()

gpointer    g_type_class_peek               (GType type);

This function is essentially the same as g_type_class_ref(), 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).

`type`�:	Type ID of a classed type.
Returns :	The GTypeClass structure for the given type ID or `NULL` if the class does not currently exist.

g_type_class_unref ()

void        g_type_class_unref              (gpointer g_class);

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 g_type_class_unref() are invalid.

g_class�: The GTypeClass structure to unreference.

g_type_class_peek_parent ()

gpointer    g_type_class_peek_parent        (gpointer g_class);

This is a convenience function, often needed in class initializers. 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:
g_type_class_peek (g_type_parent (G_TYPE_FROM_CLASS (g_class)));

`g_class`�:	The GTypeClass structure to retrieve the parent class for.
Returns :	The parent class of `g_class`.

g_type_interface_peek ()

gpointer    g_type_interface_peek           (gpointer instance_class,
                                             GType iface_type);

Returns the GTypeInterface structure of an interface to which the passed in class conforms.

`instance_class`�:	A GTypeClass structure.
`iface_type`�:	An interface ID which this class conforms to.
Returns :	The GTypeInterface structure of `iface_type`, or `NULL` if the class is not instantiated.

g_type_interface_peek_parent ()

gpointer    g_type_interface_peek_parent    (gpointer g_iface);

`g_iface`�:
Returns :

g_type_children ()

GType*      g_type_children                 (GType type,
                                             guint *n_children);

Return a newly allocated and 0-terminated array of type IDs, listing the child types of type. The return value has to be g_free()ed after use.

`type`�:	The parent type.
`n_children`�:	Optional guint pointer to contain the number of child types.
Returns :	Newly allocated and 0-terminated array of child types.

g_type_interfaces ()

GType*      g_type_interfaces               (GType type,
                                             guint *n_interfaces);

Return a newly allocated and 0-terminated array of type IDs, listing the interface types that type conforms to. The return value has to be g_free()ed after use.

`type`�:	The type to list interface types for.
`n_interfaces`�:	Optional guint pointer to contain the number of interface types.
Returns :	Newly allocated and 0-terminated array of interface types.

g_type_set_qdata ()

void        g_type_set_qdata                (GType type,
                                             GQuark quark,
                                             gpointer data);

`type`�:
`quark`�:
`data`�:

g_type_get_qdata ()

gpointer    g_type_get_qdata                (GType type,
                                             GQuark quark);

`type`�:
`quark`�:
Returns :

g_type_query ()

void        g_type_query                    (GType type,
                                             GTypeQuery *query);

`type`�:
`query`�:

struct GTypeQuery

struct GTypeQuery
{
  GType		type;
  const gchar  *type_name;
  guint		class_size;
  guint		instance_size;
};

GBaseInitFunc ()

void        (*GBaseInitFunc)                (gpointer g_class);

A callback function used by the type system to do base initialization of the class structures of derived types. It is called as part of the initialization process of all derived classes and should reallocate or reset all dynamic class members copied over from the parent class. Therefore class members, e.g. strings, that are not sufficiently handled by a plain memory copy of the parent class into the derived class have to be altered. See GClassInitFunc() for a discussion of the class intialization process.

g_class�: The GTypeClass structure to initialize.

GBaseFinalizeFunc ()

void        (*GBaseFinalizeFunc)            (gpointer g_class);

A callback function used by the type system to finalize those portions of a derived types class structure that were setup from the corresponding GBaseInitFunc() function. Class finalization basically works the inverse way in which class intialization is performed. See GClassInitFunc() for a discussion of the class intialization process.

g_class�: The GTypeClass structure to finalize.

GClassInitFunc ()

void        (*GClassInitFunc)               (gpointer g_class,
                                             gpointer class_data);

A callback function used by the type system to initialize the class of a specific type. This function should initialize all static class members. The initialization process of a class involves:

: 1 - Copying common members from the parent class over to the derived class structure.
: 2 - Zero initialization of the remaining members not copied over from the parent class.
: 3 - Invocation of the GBaseInitFunc() initializers of all parent types and the class' type.
: 4 - Invocation of the class' GClassInitFunc() initializer.

Since derived classes are partially initialized through a memory copy of the parent class, the general rule is that GBaseInitFunc() and GBaseFinalizeFunc() should take care of necessary reinitialization and release of those class members that were introduced by the type that specified these GBaseInitFunc()/GBaseFinalizeFunc(). GClassInitFunc() should only care about initializing static class members, while dynamic class members (such as allocated strings or reference counted resources) are better handled by a GBaseInitFunc() for this type, so proper initialization of the dynamic class members is performed for class initialization of derived types as well. An example may help to correspond the intend of the different class initializers:

typedef struct {
  GObjectClass parent_class;
  gint         static_integer;
  gchar       *dynamic_string;
} TypeAClass;
static void
type_a_base_class_init (TypeAClass *class)
{
  class->dynamic_string = g_strdup ("some string");
}
static void
type_a_base_class_finalize (TypeAClass *class)
{
  g_free (class->dynamic_string);
}
static void
type_a_class_init (TypeAClass *class)
{
  class->static_integer = 42;
}

typedef struct {
  TypeAClass   parent_class;
  gfloat       static_float;
  GString     *dynamic_gstring;
} TypeBClass;
static void
type_b_base_class_init (TypeBClass *class)
{
  class->dynamic_gstring = g_string_new ("some other string");
}
static void
type_b_base_class_finalize (TypeBClass *class)
{
  g_string_free (class->dynamic_gstring);
}
static void
type_b_class_init (TypeBClass *class)
{
  class->static_float = 3.14159265358979323846;
}

Initialization of TypeBClass will first cause initialization of TypeAClass (derived classes reference their parent classes, see g_type_class_ref() on this). Initialization of TypeAClass roughly involves zero-initializing its fields, then calling its GBaseInitFunc() type_a_base_class_init() that allocates its dynamic members (dynamic_string) and finally calling its GClassInitFunc() type_a_class_init() to initialize its static members (static_integer). The first step in the initialization process of TypeBClass is then a plain memory copy of the contents of TypeAClass into TypeBClass and zero-initialization of the remaining fields in TypeBClass. The dynamic members of TypeAClass within TypeBClass now need reinitialization which is performed by calling type_a_base_class_init() with an argument of TypeBClass. After that, the GBaseInitFunc() of TypeBClass, type_b_base_class_init() is called to allocate the dynamic members of TypeBClass (dynamic_gstring), and finally the GClassInitFunc() of TypeBClass, type_b_class_init(), is called to complete the initialization process with the static members (static_float). Corresponding finalization counter parts to the GBaseInitFunc() functions have to be provided to release allocated resources at class finalization time.

`g_class`�:	The GTypeClass structure to initialize.
`class_data`�:	The `class_data` member supplied via the GTypeInfo structure.

GClassFinalizeFunc ()

void        (*GClassFinalizeFunc)           (gpointer g_class,
                                             gpointer class_data);

A callback function used by the type system to finalize a class. This function is rarely needed, as dynamically allocated class resources should be handled by GBaseInitFunc() and GBaseFinalizeFunc(). Also, specification of a GClassFinalizeFunc() in the GTypeInfo structure of a static type is invalid, because classes of static types will never be finalized (they are artificially kept alive when their reference count drops to zero).

`g_class`�:	The GTypeClass structure to finalize.
`class_data`�:	The `class_data` member supplied via the GTypeInfo structure.

GInstanceInitFunc ()

void        (*GInstanceInitFunc)            (GTypeInstance *instance,
                                             gpointer g_class);

A callback function used by the type system to initialize a new instance of a type. This function initializes all instance members and allocates any resources required by it. Initialization of a derived instance involves calling all its parent types instance initializers, therefore the class member of the instance is altered during its initialization to always point to the class that belongs to the type the current initializer was introduced for.

`instance`�:	The instance to initialize.
`g_class`�:	The class of the type the instance is created for.

GInterfaceInitFunc ()

void        (*GInterfaceInitFunc)           (gpointer g_iface,
                                             gpointer iface_data);

A callback function used by the type system to initialize a new interface. This function should initialize all internal data and allocate any resources required by the interface.

`g_iface`�:	The interface structure to initialize.
`iface_data`�:	The `class_data` supplied via the GTypeInfo structure.

GInterfaceFinalizeFunc ()

void        (*GInterfaceFinalizeFunc)       (gpointer g_iface,
                                             gpointer iface_data);

A callback function used by the type system to finalize an interface. This function should destroy any internal data and release any resources allocated by the corresponding GInterfaceInitFunc() function.

`g_iface`�:	The interface structure to finalize.
`iface_data`�:	The `class_data` supplied via the GTypeInfo structure.

GTypeClassCacheFunc ()

gboolean    (*GTypeClassCacheFunc)          (gpointer cache_data,
                                             GTypeClass *g_class);

`cache_data`�:
`g_class`�:
Returns :

enum GTypeFlags

typedef enum    /*< skip >*/
{
  G_TYPE_FLAG_ABSTRACT		= (1 << 4),
  G_TYPE_FLAG_VALUE_ABSTRACT	= (1 << 5)
} GTypeFlags;

Bit masks used to check or determine characteristics of a type.

`G_TYPE_FLAG_ABSTRACT`	Indicates an abstract type. No instances can be created for an abstract type.
`G_TYPE_FLAG_VALUE_ABSTRACT`

enum GTypeFundamentalFlags

typedef enum    /*< skip >*/
{
  G_TYPE_FLAG_CLASSED           = (1 << 0),
  G_TYPE_FLAG_INSTANTIATABLE    = (1 << 1),
  G_TYPE_FLAG_DERIVABLE         = (1 << 2),
  G_TYPE_FLAG_DEEP_DERIVABLE    = (1 << 3)
} GTypeFundamentalFlags;

Bit masks used to check or determine specific characteristics of a fundamental type.

`G_TYPE_FLAG_CLASSED`	Indicates a classed type.
`G_TYPE_FLAG_INSTANTIATABLE`	Indicates an instantiable type (implies classed).
`G_TYPE_FLAG_DERIVABLE`	Indicates a flat derivable type.
`G_TYPE_FLAG_DEEP_DERIVABLE`	Indicates a deep derivable type (implies derivable).

g_type_register_static ()

GType       g_type_register_static          (GType parent_type,
                                             const gchar *type_name,
                                             const GTypeInfo *info,
                                             GTypeFlags flags);

Registers type_name as the name of a new static type derived from parent_type. The type system uses the information contained in the GTypeInfo structure pointed to by info to manage the type and its instances (if not abstract). The value of flags determines the nature (e.g. abstract or not) of the type.

`parent_type`�:	Type which this type will be derived from.
`type_name`�:	0-terminated string used as the name of the new type.
`info`�:	The GTypeInfo structure for this type.
`flags`�:	Bitwise combination of GTypeFlags values.
Returns :	The new type identifier.

g_type_register_dynamic ()

GType       g_type_register_dynamic         (GType parent_type,
                                             const gchar *type_name,
                                             GTypePlugin *plugin,
                                             GTypeFlags flags);

Registers type_name as the name of a new dynamic type derived from parent_type. The type system uses the information contained in the GTypePlugin structure pointed to by plugin to manage the type and its instances (if not abstract). The value of flags determines the nature (e.g. abstract or not) of the type.

`parent_type`�:	Type which this type will be derived from.
`type_name`�:	0-terminated string used as the name of the new type.
`plugin`�:	The GTypePlugin structure to retrieve the GTypeInfo from.
`flags`�:	Bitwise combination of GTypeFlags values.
Returns :	The new type identifier or G_TYPE_INVALID if registration failed.

g_type_register_fundamental ()

GType       g_type_register_fundamental     (GType type_id,
                                             const gchar *type_name,
                                             const GTypeInfo *info,
                                             const GTypeFundamentalInfo *finfo,
                                             GTypeFlags flags);

Registers type_id as the predefined identifier and type_name as the name of a fundamental type. The type system uses the information contained in the GTypeInfo structure pointed to by info and the GTypeFundamentalInfo structure pointed to by finfo to manage the type and its instances. The value of flags determines additional characteristics of the fundamental type.

`type_id`�:	A predefined GTypeFundamentals value.
`type_name`�:	0-terminated string used as the name of the new type.
`info`�:	The GTypeInfo structure for this type.
`finfo`�:	The GTypeFundamentalInfo structure for this type.
`flags`�:	Bitwise combination of GTypeFlags values.
Returns :	The predefined type identifier.

g_type_add_interface_static ()

void        g_type_add_interface_static     (GType instance_type,
                                             GType interface_type,
                                             const GInterfaceInfo *info);

Adds the static interface_type to instantiable_type. The information contained in the GTypeInterfaceInfo structure pointed to by info is used to manage the relationship.

`instance_type`�:	GType value of an instantiable type.
`interface_type`�:	GType value of an interface type.
`info`�:	The GInterfaceInfo structure for this (`instance_type`, `interface_type`) combination.

g_type_add_interface_dynamic ()

void        g_type_add_interface_dynamic    (GType instance_type,
                                             GType interface_type,
                                             GTypePlugin *plugin);

`instance_type`�:
`interface_type`�:
`plugin`�:

g_type_interface_add_prerequisite ()

void        g_type_interface_add_prerequisite
                                            (GType interface_type,
                                             GType prerequisite_type);

`interface_type`�:
`prerequisite_type`�:

g_type_get_plugin ()

GTypePlugin* g_type_get_plugin              (GType type);

Returns the GTypePlugin structure for type or NULL if type does not have a GTypePlugin structure.

`type`�:	The GType to retrieve the plugin for.
Returns :	The corresponding plugin if `type` is a dynamic type, `NULL` otherwise.

g_type_interface_get_plugin ()

GTypePlugin* g_type_interface_get_plugin    (GType instance_type,
                                             GType implementation_type);

`instance_type`�:
`implementation_type`�:
Returns :

g_type_fundamental_next ()

GType       g_type_fundamental_next         (void);

Returns the next free fundamental type id which can be used to register a new fundamental type with g_type_register_fundamental(). The returned type ID represents the highest currently registered fundamental type identifier.

Returns :

The nextmost fundamental type ID to be registered, or 0 if the type system ran out of fundamental type IDs.

g_type_fundamental ()

GType       g_type_fundamental              (GType type_id);

Internal function, used to extract the fundamental type ID portion. use G_TYPE_FUNDAMENTAL() instead.

`type_id`�:	valid type ID
Returns :	fundamental type ID

g_type_create_instance ()

GTypeInstance* g_type_create_instance       (GType type);

Creates and initializes an instance of type if type is valid and can be instantiated. The type system only performs basic allocation and structure setups for instances, actual instance creation should happen through functions supplied by the type's fundamental type implementation. So use of g_type_create_instance() is reserved for implementators of fundamental types only. E.g. instances of the GObject hierarchy should be created via g_object_new() and never directly through g_type_create_instance() which doesn't handle things like singleton objects or object construction. Note: Do not use this function, unless you're implementing a fundamental type. Also language bindings should not use this function but g_object_new() instead.

`type`�:	An instantiabtable type to create an instance for.
Returns :	An allocated and initialized instance, subject to further treatment by the fundamental type implementation.

g_type_free_instance ()

void        g_type_free_instance            (GTypeInstance *instance);

instance�:

g_type_add_class_cache_func ()

void        g_type_add_class_cache_func     (gpointer cache_data,
                                             GTypeClassCacheFunc cache_func);

`cache_data`�:
`cache_func`�:

g_type_remove_class_cache_func ()

void        g_type_remove_class_cache_func  (gpointer cache_data,
                                             GTypeClassCacheFunc cache_func);

`cache_data`�:
`cache_func`�:

g_type_class_unref_uncached ()

void        g_type_class_unref_uncached     (gpointer g_class);

g_class�:

g_type_value_table_peek ()

GTypeValueTable* g_type_value_table_peek    (GType type);

Returns the location of the GTypeValueTable associated with type. Note, this function should only be used from source code that implements or has internal knowledge of the implementation of type.

`type`�:	A GType value.
Returns :	Location of the GTypeValueTable associated with `type` or `NULL` if there is no GTypeValueTable associated with `type`.

G_TYPE_INVALID

#define G_TYPE_INVALID			G_TYPE_MAKE_FUNDAMENTAL (0)

G_TYPE_NONE

#define G_TYPE_NONE			G_TYPE_MAKE_FUNDAMENTAL (1)

G_TYPE_INTERFACE

#define G_TYPE_INTERFACE		G_TYPE_MAKE_FUNDAMENTAL (2)

G_TYPE_CHAR

#define G_TYPE_CHAR			G_TYPE_MAKE_FUNDAMENTAL (3)

G_TYPE_UCHAR

#define G_TYPE_UCHAR			G_TYPE_MAKE_FUNDAMENTAL (4)

G_TYPE_BOOLEAN

#define G_TYPE_BOOLEAN			G_TYPE_MAKE_FUNDAMENTAL (5)

G_TYPE_INT

#define G_TYPE_INT			G_TYPE_MAKE_FUNDAMENTAL (6)

G_TYPE_UINT

#define G_TYPE_UINT			G_TYPE_MAKE_FUNDAMENTAL (7)

G_TYPE_LONG

#define G_TYPE_LONG			G_TYPE_MAKE_FUNDAMENTAL (8)

G_TYPE_ULONG

#define G_TYPE_ULONG			G_TYPE_MAKE_FUNDAMENTAL (9)

G_TYPE_INT64

#define G_TYPE_INT64			G_TYPE_MAKE_FUNDAMENTAL (10)

G_TYPE_UINT64

#define G_TYPE_UINT64			G_TYPE_MAKE_FUNDAMENTAL (11)

G_TYPE_ENUM

#define G_TYPE_ENUM			G_TYPE_MAKE_FUNDAMENTAL (12)

G_TYPE_FLAGS

#define G_TYPE_FLAGS			G_TYPE_MAKE_FUNDAMENTAL (13)

G_TYPE_FLOAT

#define G_TYPE_FLOAT			G_TYPE_MAKE_FUNDAMENTAL (14)

G_TYPE_DOUBLE

#define G_TYPE_DOUBLE			G_TYPE_MAKE_FUNDAMENTAL (15)

G_TYPE_STRING

#define G_TYPE_STRING			G_TYPE_MAKE_FUNDAMENTAL (16)

G_TYPE_POINTER

#define G_TYPE_POINTER			G_TYPE_MAKE_FUNDAMENTAL (17)

G_TYPE_BOXED

#define G_TYPE_BOXED			G_TYPE_MAKE_FUNDAMENTAL (18)

G_TYPE_PARAM

#define G_TYPE_PARAM			G_TYPE_MAKE_FUNDAMENTAL (19)

G_TYPE_OBJECT

#define G_TYPE_OBJECT			G_TYPE_MAKE_FUNDAMENTAL (20)

G_TYPE_RESERVED_GLIB_FIRST

#define G_TYPE_RESERVED_GLIB_FIRST	(21)

G_TYPE_RESERVED_GLIB_LAST

#define G_TYPE_RESERVED_GLIB_LAST	(31)

G_TYPE_RESERVED_BSE_FIRST

#define G_TYPE_RESERVED_BSE_FIRST	(32)

G_TYPE_RESERVED_BSE_LAST

#define G_TYPE_RESERVED_BSE_LAST	(48)

G_TYPE_RESERVED_USER_FIRST

#define G_TYPE_RESERVED_USER_FIRST	(49)

GType

Name

Synopsis

Description

Details

GType

G_TYPE_FUNDAMENTAL()

G_TYPE_FUNDAMENTAL_MAX

G_TYPE_MAKE_FUNDAMENTAL()

G_TYPE_IS_ABSTRACT()

G_TYPE_IS_DERIVED()

G_TYPE_IS_FUNDAMENTAL()

G_TYPE_IS_VALUE_TYPE()

G_TYPE_HAS_VALUE_TABLE()

G_TYPE_IS_CLASSED()

G_TYPE_IS_INSTANTIATABLE()

G_TYPE_IS_DERIVABLE()

G_TYPE_IS_DEEP_DERIVABLE()

G_TYPE_IS_INTERFACE()

struct GTypeInterface

struct GTypeInstance

struct GTypeInfo

struct GTypeFundamentalInfo

struct GInterfaceInfo

struct GTypeValueTable

G_TYPE_FROM_INSTANCE()

G_TYPE_FROM_CLASS()

G_TYPE_FROM_INTERFACE()

G_TYPE_INSTANCE_GET_CLASS()

G_TYPE_INSTANCE_GET_INTERFACE()

G_TYPE_CHECK_INSTANCE()

G_TYPE_CHECK_INSTANCE_CAST()

G_TYPE_CHECK_INSTANCE_TYPE()

G_TYPE_CHECK_CLASS_CAST()

G_TYPE_CHECK_CLASS_TYPE()

G_TYPE_CHECK_VALUE()

G_TYPE_CHECK_VALUE_TYPE()

G_TYPE_FLAG_RESERVED_ID_BIT

g_type_init ()

enum GTypeDebugFlags

g_type_init_with_debug_flags ()

g_type_name ()

g_type_qname ()

g_type_from_name ()

g_type_parent ()

g_type_depth ()

g_type_next_base ()

g_type_is_a ()

g_type_class_ref ()

g_type_class_peek ()

g_type_class_unref ()

g_type_class_peek_parent ()

g_type_interface_peek ()

g_type_interface_peek_parent ()

g_type_children ()

g_type_interfaces ()

g_type_set_qdata ()

g_type_get_qdata ()

g_type_query ()

struct GTypeQuery

GBaseInitFunc ()

GBaseFinalizeFunc ()

GClassInitFunc ()

GClassFinalizeFunc ()

GInstanceInitFunc ()

GInterfaceInitFunc ()

GInterfaceFinalizeFunc ()

GTypeClassCacheFunc ()

enum GTypeFlags

enum GTypeFundamentalFlags

g_type_register_static ()

g_type_register_dynamic ()

g_type_register_fundamental ()

g_type_add_interface_static ()

g_type_add_interface_dynamic ()

g_type_interface_add_prerequisite ()

g_type_get_plugin ()

g_type_interface_get_plugin ()

g_type_fundamental_next ()

g_type_fundamental ()