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glib/gobject/gparam.h
Ryan Lortie c18462b580 GParamSpec: add g_param_spec_get_default_value() 
The way of getting the default value out of a GParamSpec is to allocate
a GValue, initialise it, then call g_param_spec_set_default() to set the
default value into that GValue.

This is exactly how we handle setting the default value for all of the
construct properties that were not explicitly passed to g_object_new().

Instead of doing the alloc/init/store on all construct properties on
every call to g_object_new(), we can cache those GValues in the private
data of the GParamSpec itself and reuse them.

This patch does not actually make that change to g_object_new() yet, but
it adds the API to GParamSpec so that a future patch to GObject can make
the change.

https://bugzilla.gnome.org/show_bug.cgi?id=698056
2013-04-23 14:39:09 -04:00

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/* GObject - GLib Type, Object, Parameter and Signal Library
* Copyright (C) 1997-1999, 2000-2001 Tim Janik and Red Hat, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General
* Public License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place, Suite 330,
* Boston, MA 02111-1307, USA.
*
* gparam.h: GParamSpec base class implementation
*/
#ifndef __G_PARAM_H__
#define __G_PARAM_H__
#if !defined (__GLIB_GOBJECT_H_INSIDE__) && !defined (GOBJECT_COMPILATION)
#error "Only <glib-object.h> can be included directly."
#endif
#include <gobject/gvalue.h>
G_BEGIN_DECLS
/* --- standard type macros --- */
/**
* G_TYPE_IS_PARAM:
* @type: a #GType ID
*
* Checks whether @type "is a" %G_TYPE_PARAM.
*/
#define G_TYPE_IS_PARAM(type) (G_TYPE_FUNDAMENTAL (type) == G_TYPE_PARAM)
/**
* G_PARAM_SPEC:
* @pspec: a valid #GParamSpec
*
* Casts a derived #GParamSpec object (e.g. of type #GParamSpecInt) into
* a #GParamSpec object.
*/
#define G_PARAM_SPEC(pspec) (G_TYPE_CHECK_INSTANCE_CAST ((pspec), G_TYPE_PARAM, GParamSpec))
/**
* G_IS_PARAM_SPEC:
* @pspec: a #GParamSpec
*
* Checks whether @pspec "is a" valid #GParamSpec structure of type %G_TYPE_PARAM
* or derived.
*/
#define G_IS_PARAM_SPEC(pspec) (G_TYPE_CHECK_INSTANCE_TYPE ((pspec), G_TYPE_PARAM))
/**
* G_PARAM_SPEC_CLASS:
* @pclass: a valid #GParamSpecClass
*
* Casts a derived #GParamSpecClass structure into a #GParamSpecClass structure.
*/
#define G_PARAM_SPEC_CLASS(pclass) (G_TYPE_CHECK_CLASS_CAST ((pclass), G_TYPE_PARAM, GParamSpecClass))
/**
* G_IS_PARAM_SPEC_CLASS:
* @pclass: a #GParamSpecClass
*
* Checks whether @pclass "is a" valid #GParamSpecClass structure of type
* %G_TYPE_PARAM or derived.
*/
#define G_IS_PARAM_SPEC_CLASS(pclass) (G_TYPE_CHECK_CLASS_TYPE ((pclass), G_TYPE_PARAM))
/**
* G_PARAM_SPEC_GET_CLASS:
* @pspec: a valid #GParamSpec
*
* Retrieves the #GParamSpecClass of a #GParamSpec.
*/
#define G_PARAM_SPEC_GET_CLASS(pspec) (G_TYPE_INSTANCE_GET_CLASS ((pspec), G_TYPE_PARAM, GParamSpecClass))
/* --- convenience macros --- */
/**
* G_PARAM_SPEC_TYPE:
* @pspec: a valid #GParamSpec
*
* Retrieves the #GType of this @pspec.
*/
#define G_PARAM_SPEC_TYPE(pspec) (G_TYPE_FROM_INSTANCE (pspec))
/**
* G_PARAM_SPEC_TYPE_NAME:
* @pspec: a valid #GParamSpec
*
* Retrieves the #GType name of this @pspec.
*/
#define G_PARAM_SPEC_TYPE_NAME(pspec) (g_type_name (G_PARAM_SPEC_TYPE (pspec)))
/**
* G_PARAM_SPEC_VALUE_TYPE:
* @pspec: a valid #GParamSpec
*
* Retrieves the #GType to initialize a #GValue for this parameter.
*/
#define G_PARAM_SPEC_VALUE_TYPE(pspec) (G_PARAM_SPEC (pspec)->value_type)
/**
* G_VALUE_HOLDS_PARAM:
* @value: a valid #GValue structure
*
* Checks whether the given #GValue can hold values derived from type %G_TYPE_PARAM.
*
* Returns: %TRUE on success.
*/
#define G_VALUE_HOLDS_PARAM(value) (G_TYPE_CHECK_VALUE_TYPE ((value), G_TYPE_PARAM))
/* --- flags --- */
/**
* GParamFlags:
* @G_PARAM_READABLE: the parameter is readable
* @G_PARAM_WRITABLE: the parameter is writable
* @G_PARAM_CONSTRUCT: the parameter will be set upon object construction
* @G_PARAM_CONSTRUCT_ONLY: the parameter will only be set upon object construction
* @G_PARAM_LAX_VALIDATION: upon parameter conversion (see g_param_value_convert())
* strict validation is not required
* @G_PARAM_STATIC_NAME: the string used as name when constructing the
* parameter is guaranteed to remain valid and
* unmodified for the lifetime of the parameter.
* Since 2.8
* @G_PARAM_STATIC_NICK: the string used as nick when constructing the
* parameter is guaranteed to remain valid and
* unmmodified for the lifetime of the parameter.
* Since 2.8
* @G_PARAM_STATIC_BLURB: the string used as blurb when constructing the
* parameter is guaranteed to remain valid and
* unmodified for the lifetime of the parameter.
* Since 2.8
* @G_PARAM_PRIVATE: internal
* @G_PARAM_DEPRECATED: the parameter is deprecated and will be removed
* in a future version. A warning will be generated if it is used
* while running with G_ENABLE_DIAGNOSTIC=1.
* Since 2.26
*
* Through the #GParamFlags flag values, certain aspects of parameters
* can be configured.
*/
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,
/* User defined flags go up to 30 */
G_PARAM_DEPRECATED = 1 << 31
} GParamFlags;
/**
* G_PARAM_READWRITE:
*
* #GParamFlags value alias for %G_PARAM_READABLE | %G_PARAM_WRITABLE.
*/
#define G_PARAM_READWRITE (G_PARAM_READABLE | G_PARAM_WRITABLE)
/**
* G_PARAM_STATIC_STRINGS:
*
* #GParamFlags value alias for %G_PARAM_STATIC_NAME | %G_PARAM_STATIC_NICK | %G_PARAM_STATIC_BLURB.
*
* Since 2.13.0
*/
#define G_PARAM_STATIC_STRINGS (G_PARAM_STATIC_NAME | G_PARAM_STATIC_NICK | G_PARAM_STATIC_BLURB)
/* bits in the range 0xffffff00 are reserved for 3rd party usage */
/**
* G_PARAM_MASK:
*
* Mask containing the bits of #GParamSpec.flags which are reserved for GLib.
*/
#define G_PARAM_MASK (0x000000ff)
/**
* G_PARAM_USER_SHIFT:
*
* Minimum shift count to be used for user defined flags, to be stored in
* #GParamSpec.flags. The maximum allowed is 30 + G_PARAM_USER_SHIFT.
*/
#define G_PARAM_USER_SHIFT (8)
/* --- typedefs & structures --- */
typedef struct _GParamSpec GParamSpec;
typedef struct _GParamSpecClass GParamSpecClass;
typedef struct _GParameter GParameter;
typedef struct _GParamSpecPool GParamSpecPool;
/**
* GParamSpec:
* @g_type_instance: private #GTypeInstance portion
* @name: name of this parameter: always an interned string
* @flags: #GParamFlags flags for this parameter
* @value_type: the #GValue type for this parameter
* @owner_type: #GType type that uses (introduces) this parameter
*
* All other fields of the <structname>GParamSpec</structname> struct are private and
* should not be used directly.
*/
struct _GParamSpec
{
GTypeInstance g_type_instance;
const gchar *name; /* interned string */
GParamFlags flags;
GType value_type;
GType owner_type; /* class or interface using this property */
/*< private >*/
gchar *_nick;
gchar *_blurb;
GData *qdata;
guint ref_count;
guint param_id; /* sort-criteria */
};
/**
* GParamSpecClass:
* @g_type_class: the parent class
* @value_type: the #GValue type for this parameter
* @finalize: The instance finalization function (optional), should chain
* up to the finalize method of the parent class.
* @value_set_default: Resets a @value to the default value for this type
* (recommended, the default is g_value_reset()), see
* g_param_value_set_default().
* @value_validate: Ensures that the contents of @value comply with the
* specifications set out by this type (optional), see
* g_param_value_validate().
* @values_cmp: Compares @value1 with @value2 according to this type
* (recommended, the default is memcmp()), see g_param_values_cmp().
*
* The class structure for the <structname>GParamSpec</structname> type.
* Normally, <structname>GParamSpec</structname> classes are filled by
* g_param_type_register_static().
*/
struct _GParamSpecClass
{
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);
/*< private >*/
gpointer dummy[4];
};
/**
* GParameter:
* @name: the parameter name
* @value: the parameter value
*
* The <structname>GParameter</structname> struct is an auxiliary structure used
* to hand parameter name/value pairs to g_object_newv().
*/
struct _GParameter /* auxiliary structure for _setv() variants */
{
const gchar *name;
GValue value;
};
/* --- prototypes --- */
GLIB_AVAILABLE_IN_ALL
GParamSpec* g_param_spec_ref (GParamSpec *pspec);
GLIB_AVAILABLE_IN_ALL
void g_param_spec_unref (GParamSpec *pspec);
GLIB_AVAILABLE_IN_ALL
void g_param_spec_sink (GParamSpec *pspec);
GLIB_AVAILABLE_IN_ALL
GParamSpec* g_param_spec_ref_sink (GParamSpec *pspec);
GLIB_AVAILABLE_IN_ALL
gpointer g_param_spec_get_qdata (GParamSpec *pspec,
GQuark quark);
GLIB_AVAILABLE_IN_ALL
void g_param_spec_set_qdata (GParamSpec *pspec,
GQuark quark,
gpointer data);
GLIB_AVAILABLE_IN_ALL
void g_param_spec_set_qdata_full (GParamSpec *pspec,
GQuark quark,
gpointer data,
GDestroyNotify destroy);
GLIB_AVAILABLE_IN_ALL
gpointer g_param_spec_steal_qdata (GParamSpec *pspec,
GQuark quark);
GLIB_AVAILABLE_IN_ALL
GParamSpec* g_param_spec_get_redirect_target (GParamSpec *pspec);
GLIB_AVAILABLE_IN_ALL
void g_param_value_set_default (GParamSpec *pspec,
GValue *value);
GLIB_AVAILABLE_IN_ALL
gboolean g_param_value_defaults (GParamSpec *pspec,
GValue *value);
GLIB_AVAILABLE_IN_ALL
gboolean g_param_value_validate (GParamSpec *pspec,
GValue *value);
GLIB_AVAILABLE_IN_ALL
gboolean g_param_value_convert (GParamSpec *pspec,
const GValue *src_value,
GValue *dest_value,
gboolean strict_validation);
GLIB_AVAILABLE_IN_ALL
gint g_param_values_cmp (GParamSpec *pspec,
const GValue *value1,
const GValue *value2);
GLIB_AVAILABLE_IN_ALL
const gchar * g_param_spec_get_name (GParamSpec *pspec);
GLIB_AVAILABLE_IN_ALL
const gchar * g_param_spec_get_nick (GParamSpec *pspec);
GLIB_AVAILABLE_IN_ALL
const gchar * g_param_spec_get_blurb (GParamSpec *pspec);
GLIB_AVAILABLE_IN_ALL
void g_value_set_param (GValue *value,
GParamSpec *param);
GLIB_AVAILABLE_IN_ALL
GParamSpec* g_value_get_param (const GValue *value);
GLIB_AVAILABLE_IN_ALL
GParamSpec* g_value_dup_param (const GValue *value);
GLIB_AVAILABLE_IN_ALL
void g_value_take_param (GValue *value,
GParamSpec *param);
GLIB_DEPRECATED_FOR(g_value_take_param)
void g_value_set_param_take_ownership (GValue *value,
GParamSpec *param);
GLIB_AVAILABLE_IN_2_36
const GValue * g_param_spec_get_default_value (GParamSpec *param);
/* --- convenience functions --- */
typedef struct _GParamSpecTypeInfo GParamSpecTypeInfo;
/**
* GParamSpecTypeInfo:
* @instance_size: Size of the instance (object) structure.
* @n_preallocs: Prior to GLib 2.10, it specified the number of pre-allocated (cached) instances to reserve memory for (0 indicates no caching). Since GLib 2.10, it is ignored, since instances are allocated with the <link linkend="glib-Memory-Slices">slice allocator</link> now.
* @instance_init: Location of the instance initialization function (optional).
* @value_type: The #GType of values conforming to this #GParamSpec
* @finalize: The instance finalization function (optional).
* @value_set_default: Resets a @value to the default value for @pspec
* (recommended, the default is g_value_reset()), see
* g_param_value_set_default().
* @value_validate: Ensures that the contents of @value comply with the
* specifications set out by @pspec (optional), see
* g_param_value_validate().
* @values_cmp: Compares @value1 with @value2 according to @pspec
* (recommended, the default is memcmp()), see g_param_values_cmp().
*
* 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 its memory
* does not need to be persistent across invocation of
* g_param_type_register_static().
*/
struct _GParamSpecTypeInfo
{
/* 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);
};
GLIB_AVAILABLE_IN_ALL
GType g_param_type_register_static (const gchar *name,
const GParamSpecTypeInfo *pspec_info);
/* For registering builting types */
GType _g_param_type_register_static_constant (const gchar *name,
const GParamSpecTypeInfo *pspec_info,
GType opt_type);
/* --- protected --- */
GLIB_AVAILABLE_IN_ALL
gpointer g_param_spec_internal (GType param_type,
const gchar *name,
const gchar *nick,
const gchar *blurb,
GParamFlags flags);
GLIB_AVAILABLE_IN_ALL
GParamSpecPool* g_param_spec_pool_new (gboolean type_prefixing);
GLIB_AVAILABLE_IN_ALL
void g_param_spec_pool_insert (GParamSpecPool *pool,
GParamSpec *pspec,
GType owner_type);
GLIB_AVAILABLE_IN_ALL
void g_param_spec_pool_remove (GParamSpecPool *pool,
GParamSpec *pspec);
GLIB_AVAILABLE_IN_ALL
GParamSpec* g_param_spec_pool_lookup (GParamSpecPool *pool,
const gchar *param_name,
GType owner_type,
gboolean walk_ancestors);
GLIB_AVAILABLE_IN_ALL
GList* g_param_spec_pool_list_owned (GParamSpecPool *pool,
GType owner_type);
GLIB_AVAILABLE_IN_ALL
GParamSpec** g_param_spec_pool_list (GParamSpecPool *pool,
GType owner_type,
guint *n_pspecs_p);
/* contracts:
*
* gboolean value_validate (GParamSpec *pspec,
* GValue *value):
* modify value contents in the least destructive way, so
* that it complies with pspec's requirements (i.e.
* according to minimum/maximum ranges etc...). return
* whether modification was necessary.
*
* gint values_cmp (GParamSpec *pspec,
* const GValue *value1,
* const GValue *value2):
* return value1 - value2, i.e. (-1) if value1 < value2,
* (+1) if value1 > value2, and (0) otherwise (equality)
*/
G_END_DECLS
#endif /* __G_PARAM_H__ */
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