| <!-- ##### SECTION Title ##### --> |
| GParamSpec |
| |
| <!-- ##### SECTION Short_Description ##### --> |
| Metadata for parameter specifications |
| |
| <!-- ##### SECTION Long_Description ##### --> |
| <para> |
| #GParamSpec is an object structure that encapsulates the metadata |
| required to specify parameters, such as e.g. #GObject properties. |
| </para> |
| <para id="canonical-parameter-name"> |
| Parameter names need to start with a letter (a-z or A-Z). Subsequent |
| characters can be letters, numbers or a '-'. |
| All other characters are replaced by a '-' during construction. |
| The result of this replacement is called the canonical name of the |
| parameter. |
| </para> |
| |
| <!-- ##### SECTION See_Also ##### --> |
| <para> |
| g_object_class_install_property(), g_object_set(), g_object_get(), |
| g_object_set_property(), g_object_get_property(), g_value_register_transform_func() |
| </para> |
| |
| <!-- ##### SECTION Stability_Level ##### --> |
| |
| |
| <!-- ##### MACRO G_TYPE_IS_PARAM ##### --> |
| <para> |
| Returns whether @type "is a" %G_TYPE_PARAM. |
| </para> |
| |
| @type: a #GType ID |
| |
| |
| <!-- ##### MACRO G_PARAM_SPEC ##### --> |
| <para> |
| Casts a derived #GParamSpec object (e.g. of type #GParamSpecInt) into |
| a #GParamSpec object. |
| </para> |
| |
| @pspec: a valid #GParamSpec |
| |
| |
| <!-- ##### MACRO G_IS_PARAM_SPEC ##### --> |
| <para> |
| Checks whether @pspec "is a" valid #GParamSpec structure of type %G_TYPE_PARAM |
| or derived. |
| </para> |
| |
| @pspec: a #GParamSpec |
| |
| |
| <!-- ##### MACRO G_PARAM_SPEC_CLASS ##### --> |
| <para> |
| Casts a derived #GParamSpecClass structure into a #GParamSpecClass structure. |
| </para> |
| |
| @pclass: a valid #GParamSpecClass |
| |
| |
| <!-- ##### MACRO G_IS_PARAM_SPEC_CLASS ##### --> |
| <para> |
| Checks whether @pclass "is a" valid #GParamSpecClass structure of type |
| %G_TYPE_PARAM or derived. |
| </para> |
| |
| @pclass: a #GParamSpecClass |
| |
| |
| <!-- ##### MACRO G_PARAM_SPEC_GET_CLASS ##### --> |
| <para> |
| Retrieves the #GParamSpecClass of a #GParamSpec. |
| </para> |
| |
| @pspec: a valid #GParamSpec |
| |
| |
| <!-- ##### MACRO G_PARAM_SPEC_TYPE ##### --> |
| <para> |
| Retrieves the #GType of this @pspec. |
| </para> |
| |
| @pspec: a valid #GParamSpec |
| |
| |
| <!-- ##### MACRO G_PARAM_SPEC_TYPE_NAME ##### --> |
| <para> |
| Retrieves the #GType name of this @pspec. |
| </para> |
| |
| @pspec: a valid #GParamSpec |
| |
| |
| <!-- ##### MACRO G_PARAM_SPEC_VALUE_TYPE ##### --> |
| <para> |
| Retrieves the #GType to initialize a #GValue for this parameter. |
| </para> |
| |
| @pspec: a valid #GParamSpec |
| |
| |
| <!-- ##### STRUCT GParamSpec ##### --> |
| <para> |
| All fields of the <structname>GParamSpec</structname> struct are private and |
| should not be used directly, except for the following: |
| </para> |
| |
| @g_type_instance: private #GTypeInstance portion |
| @name: name of this parameter |
| @flags: #GParamFlags flags for this parameter |
| @value_type: the #GValue type for this parameter |
| @owner_type: #GType type that uses (introduces) this paremeter |
| |
| <!-- ##### STRUCT GParamSpecClass ##### --> |
| <para> |
| The class structure for the <structname>GParamSpec</structname> type. |
| Normally, <structname>GParamSpec</structname> classes are filled by |
| g_param_type_register_static(). |
| </para> |
| |
| @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_set_validate(). |
| @values_cmp: Compares @value1 with @value2 according to this type |
| (recommended, the default is memcmp()), see g_param_values_cmp(). |
| |
| <!-- ##### ENUM GParamFlags ##### --> |
| <para> |
| Through the #GParamFlags flag values, certain aspects of parameters |
| can be configured. |
| </para> |
| |
| @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_PRIVATE: |
| @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 |
| |
| <!-- ##### MACRO G_PARAM_READWRITE ##### --> |
| <para> |
| #GParamFlags value alias for %G_PARAM_READABLE | %G_PARAM_WRITABLE. |
| </para> |
| |
| |
| |
| <!-- ##### MACRO G_PARAM_STATIC_STRINGS ##### --> |
| <para> |
| #GParamFlags value alias for %G_PARAM_STATIC_NAME | %G_PARAM_STATIC_NICK | %G_PARAM_STATIC_BLURB. |
| |
| Since 2.13.0 |
| </para> |
| |
| |
| |
| <!-- ##### MACRO G_PARAM_MASK ##### --> |
| <para> |
| Mask containing the bits of #GParamSpec.flags which are reserved for GLib. |
| </para> |
| |
| |
| |
| <!-- ##### MACRO G_PARAM_USER_SHIFT ##### --> |
| <para> |
| Minimum shift count to be used for user defined flags, to be stored in |
| #GParamSpec.flags. |
| </para> |
| |
| |
| |
| <!-- ##### FUNCTION g_param_spec_ref ##### --> |
| <para> |
| Increments the reference count of @pspec. |
| </para> |
| |
| @pspec: a valid #GParamSpec |
| @Returns: the #GParamSpec that was passed into this function |
| |
| |
| <!-- ##### FUNCTION g_param_spec_unref ##### --> |
| <para> |
| Decrements the reference count of a @pspec. |
| </para> |
| |
| @pspec: a valid #GParamSpec |
| |
| |
| <!-- ##### FUNCTION g_param_spec_sink ##### --> |
| <para> |
| 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 |
| <literal>g_param_spec_ref (pspec); g_param_spec_sink (pspec);</literal> |
| 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). |
| </para> |
| |
| @pspec: a valid #GParamSpec |
| |
| |
| <!-- ##### FUNCTION g_param_spec_ref_sink ##### --> |
| <para> |
| Convenience function to ref and sink a #GParamSpec. |
| </para> |
| |
| @pspec: a valid #GParamSpec |
| @Returns: the #GParamSpec that was passed into this function |
| @Since: 2.10 |
| |
| |
| <!-- ##### FUNCTION g_param_value_set_default ##### --> |
| <para> |
| Sets @value to its default value as specified in @pspec. |
| </para> |
| |
| @pspec: a valid #GParamSpec |
| @value: a #GValue of correct type for @pspec |
| |
| |
| <!-- ##### FUNCTION g_param_value_defaults ##### --> |
| <para> |
| Checks whether @value contains the default value as specified in @pspec. |
| </para> |
| |
| @pspec: a valid #GParamSpec |
| @value: a #GValue of correct type for @pspec |
| @Returns: whether @value contains the canonical default for this @pspec |
| |
| |
| <!-- ##### FUNCTION g_param_value_validate ##### --> |
| <para> |
| 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. |
| </para> |
| |
| @pspec: a valid #GParamSpec |
| @value: a #GValue of correct type for @pspec |
| @Returns: whether modifying @value was necessary to ensure validity |
| |
| |
| <!-- ##### FUNCTION g_param_value_convert ##### --> |
| <para> |
| 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(). |
| </para> |
| |
| @pspec: a valid #GParamSpec |
| @src_value: souce #GValue |
| @dest_value: destination #GValue of correct type for @pspec |
| @strict_validation: %TRUE requires @dest_value to conform to @pspec without modifications |
| @Returns: %TRUE if transformation and validation were successful, |
| %FALSE otherwise and @dest_value is left untouched. |
| |
| |
| <!-- ##### FUNCTION g_param_values_cmp ##### --> |
| <para> |
| 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. |
| </para> |
| |
| @pspec: a valid #GParamSpec |
| @value1: a #GValue of correct type for @pspec |
| @value2: a #GValue of correct type for @pspec |
| @Returns: -1, 0 or +1, for a less than, equal to or greater than result |
| |
| |
| <!-- ##### FUNCTION g_param_spec_get_name ##### --> |
| <para> |
| Returns the name of a #GParamSpec. |
| </para> |
| |
| @pspec: a valid #GParamSpec |
| @Returns: the name of @pspec. |
| |
| |
| <!-- ##### FUNCTION g_param_spec_get_nick ##### --> |
| <para> |
| Returns the nickname of a #GParamSpec. |
| </para> |
| |
| @pspec: a valid #GParamSpec |
| @Returns: the nickname of @pspec. |
| |
| |
| <!-- ##### FUNCTION g_param_spec_get_blurb ##### --> |
| <para> |
| Returns the short description of a #GParamSpec. |
| </para> |
| |
| @pspec: a valid #GParamSpec |
| @Returns: the short description of @pspec. |
| |
| |
| <!-- ##### FUNCTION g_param_spec_get_qdata ##### --> |
| <para> |
| Gets back user data pointers stored via g_param_spec_set_qdata(). |
| </para> |
| |
| @pspec: a valid #GParamSpec |
| @quark: a #GQuark, naming the user data pointer |
| @Returns: the user data pointer set, or %NULL |
| |
| |
| <!-- ##### FUNCTION g_param_spec_set_qdata ##### --> |
| <para> |
| 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. |
| </para> |
| |
| @pspec: the #GParamSpec to set store a user data pointer |
| @quark: a #GQuark, naming the user data pointer |
| @data: an opaque user data pointer |
| |
| |
| <!-- ##### FUNCTION g_param_spec_set_qdata_full ##### --> |
| <para> |
| This function works like g_param_spec_set_qdata(), but in addition, |
| a <literal>void (*destroy) (gpointer)</literal> 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. |
| </para> |
| |
| @pspec: the #GParamSpec to set store a user data pointer |
| @quark: a #GQuark, naming the user data pointer |
| @data: an opaque user data pointer |
| @destroy: function to invoke with @data as argument, when @data needs to |
| be freed |
| |
| |
| <!-- ##### FUNCTION g_param_spec_steal_qdata ##### --> |
| <para> |
| 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. |
| </para> |
| |
| @pspec: the #GParamSpec to get a stored user data pointer from |
| @quark: a #GQuark, naming the user data pointer |
| @Returns: the user data pointer set, or %NULL |
| |
| |
| <!-- ##### FUNCTION g_param_spec_get_redirect_target ##### --> |
| <para> |
| 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. |
| </para> |
| |
| @pspec: a #GParamSpec |
| @Returns: paramspec to which requests on this paramspec should |
| be redirected, or %NULL if none. |
| @Since: 2.4 |
| |
| |
| <!-- ##### FUNCTION g_param_spec_internal ##### --> |
| <para> |
| Creates a new #GParamSpec instance. |
| </para> |
| <para> |
| 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. |
| </para> |
| <para> |
| 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. |
| </para> |
| <para> |
| Beyond the name, #GParamSpec<!-- -->s 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. |
| </para> |
| |
| @param_type: the #GType for the property; must be derived from #G_TYPE_PARAM |
| @name: the canonical name of the property |
| @nick: the nickname of the property |
| @blurb: a short description of the property |
| @flags: a combination of #GParamFlags |
| @Returns: a newly allocated #GParamSpec instance |
| |
| |
| <!-- ##### STRUCT GParamSpecTypeInfo ##### --> |
| <para> |
| 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(). |
| </para> |
| |
| @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_set_validate(). |
| @values_cmp: Compares @value1 with @value2 according to @pspec |
| (recommended, the default is memcmp()), see g_param_values_cmp(). |
| |
| <!-- ##### FUNCTION g_param_type_register_static ##### --> |
| <para> |
| 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. |
| </para> |
| |
| @name: 0-terminated string used as the name of the new #GParamSpec type. |
| @pspec_info: The #GParamSpecTypeInfo for this #GParamSpec type. |
| @Returns: The new type identifier. |
| |
| |
| <!-- ##### STRUCT GParamSpecPool ##### --> |
| <para> |
| A #GParamSpecPool maintains a collection of #GParamSpec<!-- -->s 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. |
| </para> |
| |
| |
| <!-- ##### FUNCTION g_param_spec_pool_new ##### --> |
| <para> |
| Creates a new #GParamSpecPool. |
| </para> |
| <para> |
| 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. |
| </para> |
| |
| @type_prefixing: Whether the pool will support type-prefixed property names. |
| @Returns: a newly allocated #GParamSpecPool. |
| |
| |
| <!-- ##### FUNCTION g_param_spec_pool_insert ##### --> |
| <para> |
| Inserts a #GParamSpec in the pool. |
| </para> |
| |
| @pool: a #GParamSpecPool. |
| @pspec: the #GParamSpec to insert |
| @owner_type: a #GType identifying the owner of @pspec |
| |
| |
| <!-- ##### FUNCTION g_param_spec_pool_remove ##### --> |
| <para> |
| Removes a #GParamSpec from the pool. |
| </para> |
| |
| @pool: a #GParamSpecPool |
| @pspec: the #GParamSpec to remove |
| |
| |
| <!-- ##### FUNCTION g_param_spec_pool_lookup ##### --> |
| <para> |
| Looks up a #GParamSpec in the pool. |
| </para> |
| |
| @pool: a #GParamSpecPool |
| @param_name: the name to look for |
| @owner_type: the owner to look for |
| @walk_ancestors: If %TRUE, also try to find a #GParamSpec with @param_name |
| owned by an ancestor of @owner_type. |
| @Returns: The found #GParamSpec, or %NULL if no matching #GParamSpec was found. |
| |
| |
| <!-- ##### FUNCTION g_param_spec_pool_list ##### --> |
| <para> |
| Gets an array of all #GParamSpec<!-- -->s owned by @owner_type in the pool. |
| </para> |
| |
| @pool: a #GParamSpecPool |
| @owner_type: the owner to look for |
| @n_pspecs_p: return location for the length of the returned array |
| @Returns: a newly allocated array containing pointers to all |
| #GParamSpec<!-- -->s owned by @owner_type in the pool |
| |
| |
| <!-- ##### FUNCTION g_param_spec_pool_list_owned ##### --> |
| <para> |
| Gets an #GList of all #GParamSpec<!-- -->s owned by @owner_type in the pool. |
| </para> |
| |
| @pool: a #GParamSpecPool |
| @owner_type: the owner to look for |
| @Returns: a #GList of all #GParamSpec<!-- -->s owned by @owner_type in |
| the pool#GParamSpec<!-- -->s. |
| |
| |