GNOME Documentation Library

G_TYPE_IS_PARAM()

#define G_TYPE_IS_PARAM(type)		(G_TYPE_FUNDAMENTAL (type) == G_TYPE_PARAM)

Checks whether type "is a" G_TYPE_PARAM.

G_PARAM_SPEC()

#define G_PARAM_SPEC(pspec)		(G_TYPE_CHECK_INSTANCE_CAST ((pspec), G_TYPE_PARAM, GParamSpec))

Casts a derived GParamSpec object (e.g. of type GParamSpecInt) into a GParamSpec object.

G_IS_PARAM_SPEC()

#define G_IS_PARAM_SPEC(pspec)		(G_TYPE_CHECK_INSTANCE_TYPE ((pspec), G_TYPE_PARAM))

Checks whether pspec "is a" valid GParamSpec structure of type G_TYPE_PARAM or derived.

G_PARAM_SPEC_CLASS()

#define G_PARAM_SPEC_CLASS(pclass)      (G_TYPE_CHECK_CLASS_CAST ((pclass), G_TYPE_PARAM, GParamSpecClass))

Casts a derived GParamSpecClass structure into a GParamSpecClass structure.

G_IS_PARAM_SPEC_CLASS()

#define G_IS_PARAM_SPEC_CLASS(pclass)   (G_TYPE_CHECK_CLASS_TYPE ((pclass), G_TYPE_PARAM))

Checks whether pclass "is a" valid GParamSpecClass structure of type G_TYPE_PARAM or derived.

G_PARAM_SPEC_GET_CLASS()

#define G_PARAM_SPEC_GET_CLASS(pspec)	(G_TYPE_INSTANCE_GET_CLASS ((pspec), G_TYPE_PARAM, GParamSpecClass))

Retrieves the GParamSpecClass of a GParamSpec.

G_PARAM_SPEC_TYPE()

#define G_PARAM_SPEC_TYPE(pspec)	(G_TYPE_FROM_INSTANCE (pspec))

Retrieves the GType of this pspec.

G_PARAM_SPEC_TYPE_NAME()

#define G_PARAM_SPEC_TYPE_NAME(pspec)	(g_type_name (G_PARAM_SPEC_TYPE (pspec)))

Retrieves the GType name of this pspec.

G_PARAM_SPEC_VALUE_TYPE()

#define	G_PARAM_SPEC_VALUE_TYPE(pspec)	(G_PARAM_SPEC (pspec)->value_type)

Retrieves the GType to initialize a GValue for this parameter.

GParamSpec

typedef struct {
  GTypeInstance  g_type_instance;

  gchar         *name;
  GParamFlags    flags;
  GType		 value_type;
  GType		 owner_type;	/* class or interface using this property */
} GParamSpec;

All other fields of the GParamSpec struct are private and should not be used directly.

GParamSpecClass

typedef struct {
  GTypeClass      g_type_class;

  GType		  value_type;

  void	        (*finalize)		(GParamSpec   *pspec);

  /* GParam methods */
  void          (*value_set_default)    (GParamSpec   *pspec,
					 GValue       *value);
  gboolean      (*value_validate)       (GParamSpec   *pspec,
					 GValue       *value);
  gint          (*values_cmp)           (GParamSpec   *pspec,
					 const GValue *value1,
					 const GValue *value2);
} GParamSpecClass;

The class structure for the GParamSpec type. Normally, GParamSpec classes are filled by g_param_type_register_static().

enum GParamFlags

typedef enum
{
  G_PARAM_READABLE            = 1 << 0,
  G_PARAM_WRITABLE            = 1 << 1,
  G_PARAM_CONSTRUCT	      = 1 << 2,
  G_PARAM_CONSTRUCT_ONLY      = 1 << 3,
  G_PARAM_LAX_VALIDATION      = 1 << 4,
  G_PARAM_STATIC_NAME	      = 1 << 5,
#ifndef G_DISABLE_DEPRECATED
  G_PARAM_PRIVATE	      = G_PARAM_STATIC_NAME,
#endif
  G_PARAM_STATIC_NICK	      = 1 << 6,
  G_PARAM_STATIC_BLURB	      = 1 << 7
} GParamFlags;

Through the GParamFlags flag values, certain aspects of parameters can be configured.

G_PARAM_READWRITE

#define	G_PARAM_READWRITE	(G_PARAM_READABLE | G_PARAM_WRITABLE)

GParamFlags value alias for G_PARAM_READABLE | G_PARAM_WRITABLE.

G_PARAM_STATIC_STRINGS

#define	G_PARAM_STATIC_STRINGS (G_PARAM_STATIC_NAME | G_PARAM_STATIC_NICK | G_PARAM_STATIC_BLURB)

GParamFlags value alias for G_PARAM_STATIC_NAME | G_PARAM_STATIC_NICK | G_PARAM_STATIC_BLURB.

Since 2.13.0

G_PARAM_MASK

#define	G_PARAM_MASK		(0x000000ff)

Mask containing the bits of GParamSpec.flags which are reserved for GLib.

G_PARAM_USER_SHIFT

#define	G_PARAM_USER_SHIFT	(8)

Minimum shift count to be used for user defined flags, to be stored in GParamSpec.flags.

g_param_spec_ref ()

GParamSpec*         g_param_spec_ref                    (GParamSpec *pspec);

Increments the reference count of pspec.

g_param_spec_unref ()

void                g_param_spec_unref                  (GParamSpec *pspec);

Decrements the reference count of a pspec.

g_param_spec_sink ()

void                g_param_spec_sink                   (GParamSpec *pspec);

The initial reference count of a newly created GParamSpec is 1, even though no one has explicitly called g_param_spec_ref() on it yet. So the initial reference count is flagged as "floating", until someone calls g_param_spec_ref (pspec); g_param_spec_sink (pspec); in sequence on it, taking over the initial reference count (thus ending up with a pspec that has a reference count of 1 still, but is not flagged "floating" anymore).

g_param_spec_ref_sink ()

GParamSpec*         g_param_spec_ref_sink               (GParamSpec *pspec);

Convenience function to ref and sink a GParamSpec.

Since 2.10

g_param_value_set_default ()

void                g_param_value_set_default           (GParamSpec *pspec,
                                                         GValue *value);

Sets value to its default value as specified in pspec.

g_param_value_defaults ()

gboolean            g_param_value_defaults              (GParamSpec *pspec,
                                                         GValue *value);

Checks whether value contains the default value as specified in pspec.

g_param_value_validate ()

gboolean            g_param_value_validate              (GParamSpec *pspec,
                                                         GValue *value);

Ensures that the contents of value comply with the specifications set out by pspec. For example, a GParamSpecInt might require that integers stored in value may not be smaller than -42 and not be greater than +42. If value contains an integer outside of this range, it is modified accordingly, so the resulting value will fit into the range -42 .. +42.

g_param_value_convert ()

gboolean            g_param_value_convert               (GParamSpec *pspec,
                                                         const GValue *src_value,
                                                         GValue *dest_value,
                                                         gboolean strict_validation);

Transforms src_value into dest_value if possible, and then validates dest_value, in order for it to conform to pspec. If strict_validation is TRUE this function will only succeed if the transformed dest_value complied to pspec without modifications.

See also g_value_type_transformable(), g_value_transform() and g_param_value_validate().

g_param_values_cmp ()

gint                g_param_values_cmp                  (GParamSpec *pspec,
                                                         const GValue *value1,
                                                         const GValue *value2);

Compares value1 with value2 according to pspec, and return -1, 0 or +1, if value1 is found to be less than, equal to or greater than value2, respectively.

g_param_spec_get_name ()

const gchar*        g_param_spec_get_name               (GParamSpec *pspec);

Get the name of a GParamSpec.

g_param_spec_get_nick ()

const gchar*        g_param_spec_get_nick               (GParamSpec *pspec);

Get the nickname of a GParamSpec.

g_param_spec_get_blurb ()

const gchar*        g_param_spec_get_blurb              (GParamSpec *pspec);

Get the short description of a GParamSpec.

g_param_spec_get_qdata ()

gpointer            g_param_spec_get_qdata              (GParamSpec *pspec,
                                                         GQuark quark);

Gets back user data pointers stored via g_param_spec_set_qdata().

g_param_spec_set_qdata ()

void                g_param_spec_set_qdata              (GParamSpec *pspec,
                                                         GQuark quark,
                                                         gpointer data);

Sets an opaque, named pointer on a GParamSpec. The name is specified through a GQuark (retrieved e.g. via g_quark_from_static_string()), and the pointer can be gotten back from the pspec with g_param_spec_get_qdata(). Setting a previously set user data pointer, overrides (frees) the old pointer set, using NULL as pointer essentially removes the data stored.

g_param_spec_set_qdata_full ()

void                g_param_spec_set_qdata_full         (GParamSpec *pspec,
                                                         GQuark quark,
                                                         gpointer data,
                                                         GDestroyNotify destroy);

This function works like g_param_spec_set_qdata(), but in addition, a void (*destroy) (gpointer) function may be specified which is called with data as argument when the pspec is finalized, or the data is being overwritten by a call to g_param_spec_set_qdata() with the same quark.

g_param_spec_steal_qdata ()

gpointer            g_param_spec_steal_qdata            (GParamSpec *pspec,
                                                         GQuark quark);

Gets back user data pointers stored via g_param_spec_set_qdata() and removes the data from pspec without invoking it's destroy() function (if any was set). Usually, calling this function is only required to update user data pointers with a destroy notifier.

g_param_spec_get_redirect_target ()

GParamSpec*         g_param_spec_get_redirect_target    (GParamSpec *pspec);

If the paramspec redirects operations to another paramspec, returns that paramspec. Redirect is used typically for providing a new implementation of a property in a derived type while preserving all the properties from the parent type. Redirection is established by creating a property of type GParamSpecOverride. See g_object_class_override_property() for an example of the use of this capability.

Since 2.4

g_param_spec_internal ()

gpointer            g_param_spec_internal               (GType param_type,
                                                         const gchar *name,
                                                         const gchar *nick,
                                                         const gchar *blurb,
                                                         GParamFlags flags);

Creates a new GParamSpec instance.

A property name consists of segments consisting of ASCII letters and digits, separated by either the '-' or '_' character. The first character of a property name must be a letter. Names which violate these rules lead to undefined behaviour.

When creating and looking up a GParamSpec, either separator can be used, but they cannot be mixed. Using '-' is considerably more efficient and in fact required when using property names as detail strings for signals.

Beyond the name, GParamSpecs have two more descriptive strings associated with them, the nick, which should be suitable for use as a label for the property in a property editor, and the blurb, which should be a somewhat longer description, suitable for e.g. a tooltip. The nick and blurb should ideally be localized.

GParamSpecTypeInfo

typedef struct {
  /* type system portion */
  guint16         instance_size;                               /* obligatory */
  guint16         n_preallocs;                                 /* optional */
  void		(*instance_init)	(GParamSpec   *pspec); /* optional */

  /* class portion */
  GType           value_type;				       /* obligatory */
  void          (*finalize)             (GParamSpec   *pspec); /* optional */
  void          (*value_set_default)    (GParamSpec   *pspec,  /* recommended */
					 GValue       *value);
  gboolean      (*value_validate)       (GParamSpec   *pspec,  /* optional */
					 GValue       *value);
  gint          (*values_cmp)           (GParamSpec   *pspec,  /* recommended */
					 const GValue *value1,
					 const GValue *value2);
} GParamSpecTypeInfo;

This structure is used to provide the type system with the information required to initialize and destruct (finalize) a parameter's class and instances thereof. The initialized structure is passed to the g_param_type_register_static() 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_param_type_register_static().

g_param_type_register_static ()

GType               g_param_type_register_static        (const gchar *name,
                                                         const GParamSpecTypeInfo *pspec_info);

Registers name as the name of a new static type derived from G_TYPE_PARAM. The type system uses the information contained in the GParamSpecTypeInfo structure pointed to by info to manage the GParamSpec type and its instances.

GParamSpecPool

typedef struct _GParamSpecPool GParamSpecPool;

A GParamSpecPool maintains a collection of GParamSpecs which can be quickly accessed by owner and name. The implementation of the GObject property system uses such a pool to store the GParamSpecs of the properties all object types.

g_param_spec_pool_new ()

GParamSpecPool*     g_param_spec_pool_new               (gboolean type_prefixing);

Creates a new GParamSpecPool.

If type_prefixing is TRUE, lookups in the newly created pool will allow to specify the owner as a colon-separated prefix of the property name, like "GtkContainer:border-width". This feature is deprecated, so you should always set type_prefixing to FALSE.

g_param_spec_pool_insert ()

void                g_param_spec_pool_insert            (GParamSpecPool *pool,
                                                         GParamSpec *pspec,
                                                         GType owner_type);

Inserts a GParamSpec in the pool.

g_param_spec_pool_remove ()

void                g_param_spec_pool_remove            (GParamSpecPool *pool,
                                                         GParamSpec *pspec);

Removes a GParamSpec from the pool.

g_param_spec_pool_lookup ()

GParamSpec*         g_param_spec_pool_lookup            (GParamSpecPool *pool,
                                                         const gchar *param_name,
                                                         GType owner_type,
                                                         gboolean walk_ancestors);

Looks up a GParamSpec in the pool.

g_param_spec_pool_list ()

GParamSpec**        g_param_spec_pool_list              (GParamSpecPool *pool,
                                                         GType owner_type,
                                                         guint *n_pspecs_p);

Gets an array of all GParamSpecs owned by owner_type in the pool.

g_param_spec_pool_list_owned ()

GList*              g_param_spec_pool_list_owned        (GParamSpecPool *pool,
                                                         GType owner_type);

Gets an GList of all GParamSpecs owned by owner_type in the pool.