## GBoxed

GBoxed — 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_DATE
    #define     G_TYPE_GSTRING
    #define     G_TYPE_STRV
    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_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);

Since 2.4

### GStrv

    typedef gchar** GStrv;

A C representable type name for G_TYPE_STRV.

## See Also

GParamSpecBoxed, `g_param_spec_boxed()`