Enums and Flags
Enumeration and flags types
The GLib type system provides fundamental types for enumeration and flags types. (Flags types
are like enumerations, but allow their values to be combined by bitwise or). A registered
enumeration or flags type associates a name and a nickname with each allowed value, and
the methods g_enum_get_value_by_name(), g_enum_get_value_by_nick(), g_flags_get_value_by_name()
and g_flags_get_value_by_nick() can look up values by their name or nickname.
When an enumeration or flags type is registered with the GLib type system, it can
be used as value type for object properties, using g_param_spec_enum() or
g_param_spec_flags().
GObject ships with a utility called glib-mkenums that can
construct suitable type registration functions from C enumeration definitions.
#GParamSpecEnum, #GParamSpecFlags, g_param_spec_enum(), g_param_spec_flags(),
glib-mkenums
The class of an enumeration type holds information about its
possible values.
@g_type_class: the parent class
@minimum: the smallest possible value.
@maximum: the largest possible value.
@n_values: the number of possible values.
@values: an array of #GEnumValue structs describing the
individual values.
The class of a flags type holds information about its
possible values.
@g_type_class: the parent class
@mask: a mask covering all possible values.
@n_values: the number of possible values.
@values: an array of #GFlagsValue structs describing the
individual values.
Returns the type identifier from a given #GEnumClass structure.
@class: a #GEnumClass
Returns the static type name from a given #GEnumClass structure.
@class: a #GEnumClass
Returns whether @type "is a" %G_TYPE_ENUM.
@type: a #GType ID.
Casts a derived #GEnumClass structure into a #GEnumClass structure.
@class: a valid #GEnumClass
Checks whether @class "is a" valid #GEnumClass structure of type %G_TYPE_ENUM
or derived.
@class: a #GEnumClass
Returns whether @type "is a" %G_TYPE_FLAGS.
@type: a #GType ID.
Casts a derived #GFlagsClass structure into a #GFlagsClass structure.
@class: a valid #GFlagsClass
Checks whether @class "is a" valid #GFlagsClass structure of type %G_TYPE_FLAGS
or derived.
@class: a #GFlagsClass
Returns the type identifier from a given #GFlagsClass structure.
@class: a #GFlagsClass
Returns the static type name from a given #GFlagsClass structure.
@class: a #GFlagsClass
A structure which contains a single enum value, it's name, and it's
nickname.
@value: the enum value
@value_name: the name of the value
@value_nick: the nickname of the value
A structure which contains a single flags value, it's name, and it's
nickname.
@value: the flags value
@value_name: the name of the value
@value_nick: the nickname of the value
Returns the #GEnumValue for a value.
@enum_class: a #GEnumClass
@value: the value to look up
@Returns: the #GEnumValue for @value, or %NULL if @value is not
a member of the enumeration
Looks up a #GEnumValue by name.
@enum_class: a #GEnumClass
@name: the name to look up
@Returns: the #GEnumValue with name @name, or %NULL if the enumeration doesn'
t have a member with that name
Looks up a #GEnumValue by nickname.
@enum_class: a #GEnumClass
@nick: the nickname to look up
@Returns: the #GEnumValue with nickname @nick, or %NULL if the enumeration doesn'
t have a member with that nickname
Returns the first #GFlagsValue which is set in @value.
@flags_class: a #GFlagsClass
@value: the value
@Returns: the first #GFlagsValue which is set in @value, or %NULL if none is set
Looks up a #GFlagsValue by name.
@flags_class: a #GFlagsClass
@name: the name to look up
@Returns: the #GFlagsValue with name @name, or %NULL if there is no flag with
that name
Looks up a #GFlagsValue by nickname.
@flags_class: a #GFlagsClass
@nick: the nickname to look up
@Returns: the #GFlagsValue with nickname @nick, or %NULL if there is no flag
with that nickname
Registers a new static enumeration type with the name @name.
It is normally more convenient to let glib-mkenums
generate a my_enum_get_type() function from a usual C enumeration definition
than to write one yourself using g_enum_register_static().
@name: A nul-terminated string used as the name of the new type.
@const_static_values: An array of #GEnumValue structs for the possible
enumeration values. The array is terminated by a struct with all
members being 0. GObject keeps a reference to the data, so it cannot
be stack-allocated.
@Returns: The new type identifier.
Registers a new static flags type with the name @name.
It is normally more convenient to let glib-mkenums
generate a my_flags_get_type() function from a usual C enumeration definition
than to write one yourself using g_flags_register_static().
@name: A nul-terminated string used as the name of the new type.
@const_static_values: An array of #GFlagsValue structs for the possible
flags values. The array is terminated by a struct with all members being 0.
GObject keeps a reference to the data, so it cannot be stack-allocated.
@Returns: The new type identifier.
This function is meant to be called from the complete_type_info() function
of a #GTypePlugin implementation, as in the following example:
static void
my_enum_complete_type_info (GTypePlugin *plugin,
GType g_type,
GTypeInfo *info,
GTypeValueTable *value_table)
{
static const GEnumValue values[] = {
{ MY_ENUM_FOO, "MY_ENUM_FOO", "foo" },
{ MY_ENUM_BAR, "MY_ENUM_BAR", "bar" },
{ 0, NULL, NULL }
};
g_enum_complete_type_info (type, info, values);
}
@g_enum_type: the type identifier of the type being completed
@info: the #GTypeInfo struct to be filled in
@const_values: An array of #GEnumValue structs for the possible
enumeration values. The array is terminated by a struct with all
members being 0.
This function is meant to be called from the complete_type_info() function
of a #GTypePlugin implementation, see the example for
g_enumeration_complete_type_info() above.
@g_flags_type: the type identifier of the type being completed
@info: the #GTypeInfo struct to be filled in
@const_values: An array of #GFlagsValue structs for the possible
enumeration values. The array is terminated by a struct with all
members being 0.