Boxed Types

Boxed Types — A mechanism to wrap opaque C structures registered by the type system

Synopsis


#include <glib-object.h>

gpointer            (*GBoxedCopyFunc)                   (gpointer boxed);
void                (*GBoxedFreeFunc)                   (gpointer boxed);
gpointer            g_boxed_copy                        (GType boxed_type,
                                                         gconstpointer src_boxed);
void                g_boxed_free                        (GType boxed_type,
                                                         gpointer boxed);
GType               g_boxed_type_register_static        (const gchar *name,
                                                         GBoxedCopyFunc boxed_copy,
                                                         GBoxedFreeFunc boxed_free);
GType               g_pointer_type_register_static      (const gchar *name);

#define             G_TYPE_HASH_TABLE
#define             G_TYPE_DATE
#define             G_TYPE_GSTRING
#define             G_TYPE_STRV
#define             G_TYPE_REGEX
typedef             GStrv;

Description

GBoxed is a generic wrapper mechanism for arbitrary C structures. The only thing the type system needs to know about the structures is how to copy and free them, beyond that they are treated as opaque chunks of memory.

Boxed types are useful for simple value-holder structures like rectangles or points. They can also be used for wrapping structures defined in non-GObject based libraries.

Details

GBoxedCopyFunc ()

gpointer            (*GBoxedCopyFunc)                   (gpointer boxed);

This function is provided by the user and should produce a copy of the passed in boxed structure.

`boxed` :	The boxed structure to be copied.
Returns :	The newly created copy of the boxed structure.

GBoxedFreeFunc ()

void                (*GBoxedFreeFunc)                   (gpointer boxed);

This function is provided by the user and should free the boxed structure passed.

boxed : The boxed structure to be freed.

g_boxed_copy ()

gpointer            g_boxed_copy                        (GType boxed_type,
                                                         gconstpointer src_boxed);

Provide a copy of a boxed structure src_boxed which is of type boxed_type.

`boxed_type` :	The type of `src_boxed`.
`src_boxed` :	The boxed structure to be copied.
Returns :	The newly created copy of the boxed structure.

g_boxed_free ()

void                g_boxed_free                        (GType boxed_type,
                                                         gpointer boxed);

Free the boxed structure boxed which is of type boxed_type.

`boxed_type` :	The type of `boxed`.
`boxed` :	The boxed structure to be freed.

g_boxed_type_register_static ()

GType               g_boxed_type_register_static        (const gchar *name,
                                                         GBoxedCopyFunc boxed_copy,
                                                         GBoxedFreeFunc boxed_free);

This function creates a new G_TYPE_BOXED derived type id for a new boxed type with name name. Boxed type handling functions have to be provided to copy and free opaque boxed structures of this type.

`name` :	Name of the new boxed type.
`boxed_copy` :	Boxed structure copy function.
`boxed_free` :	Boxed structure free function.
Returns :	New `G_TYPE_BOXED` derived type id for `name`.

g_pointer_type_register_static ()

GType               g_pointer_type_register_static      (const gchar *name);

Creates a new G_TYPE_POINTER derived type id for a new pointer type with name name.

`name` :	the name of the new pointer type.
Returns :	a new `G_TYPE_POINTER` derived type id for `name`.

G_TYPE_HASH_TABLE

#define	G_TYPE_HASH_TABLE (g_hash_table_get_type ())

The GType for a boxed type holding a GHashTable reference.

Since 2.10

G_TYPE_DATE

#define	G_TYPE_DATE	        (g_date_get_type ())

The GType for GDate.

G_TYPE_GSTRING

#define	G_TYPE_GSTRING		(g_gstring_get_type ())

The GType for GString.

G_TYPE_STRV

#define	G_TYPE_STRV	        (g_strv_get_type ())

The GType for a boxed type holding a NULL-terminated array of strings.

The code fragments in the following example show the use of a property of type G_TYPE_STRV with g_object_class_install_property(), g_object_set() and g_object_get().

g_object_class_install_property (object_class,
                                 PROP_AUTHORS,
                                 g_param_spec_boxed ("authors",
                                                     _("Authors"),
                                                     _("List of authors"),
                                                     G_TYPE_STRV,
                                                     G_PARAM_READWRITE));


gchar *authors[] = { "Owen", "Tim", NULL };
g_object_set (obj, "authors", authors, NULL);


gchar *writers[];
g_object_get (obj, "authors", &writers, NULL);
// do something with writers
g_strfreev (writers);