module GObject::TypePlugin
Overview
An interface that handles the lifecycle of dynamically loaded types.
The GObject type system supports dynamic loading of types. It goes as follows:
- The type is initially introduced (usually upon loading the module the first time, or by your main application that knows what modules introduces what types), like this:
WARNING ⚠️ The following code is in c ⚠️
new_type_id = g_type_register_dynamic (parent_type_id,
"TypeName",
new_type_plugin,
type_flags);
where new_type_plugin
is an implementation of the
GTypePlugin
interface.
-
The type's implementation is referenced, e.g. through
GObject::TypeClass#ref
or throughGObject::type_create_instance
(this is being called byGObject::Object.new
) or through one of the above done on a type derived fromnew_type_id
. -
This causes the type system to load the type's implementation by calling
GObject::TypePlugin#use
andGObject::TypePlugin#complete_type_info
onnew_type_plugin
. -
At some point the type's implementation isn't required anymore, e.g. after
GObject::TypeClass#unref
orGObject::type_free_instance
(called when the reference count of an instance drops to zero). -
This causes the type system to throw away the information retrieved from
GObject::TypePlugin#complete_type_info
and then it callsGObject::TypePlugin#unuse
onnew_type_plugin
. -
Things may repeat from the second step.
So basically, you need to implement a GTypePlugin
type that
carries a use_count, once use_count goes from zero to one, you need
to load the implementation to successfully handle the upcoming
GObject::TypePlugin#complete_type_info
call. Later, maybe after
succeeding use/unuse calls, once use_count drops to zero, you can
unload the implementation again. The type system makes sure to call
GObject::TypePlugin#use
and GObject::TypePlugin#complete_type_info
again when the type is needed again.
GObject::TypeModule
is an implementation of GTypePlugin
that
already implements most of this except for the actual module loading and
unloading. It even handles multiple registered types per module.
Direct including types
Defined in:
lib/gi-crystal/src/auto/g_object-2.0/type_plugin.crConstructors
-
.cast(obj : GObject::Object) : self
Cast a
GObject::Object
toself
, throws aTypeCastError
if the cast can't be made.
Class Method Summary
Instance Method Summary
- #complete_interface_info(instance_type : UInt64, interface_type : UInt64, info : GObject::InterfaceInfo) : Nil
- #complete_type_info(g_type : UInt64, info : GObject::TypeInfo, value_table : GObject::TypeValueTable) : Nil
- #to_unsafe
- #unuse : Nil
- #use : Nil