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:

  1. 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: |[ 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.

  2. The type's implementation is referenced, e.g. through g_type_class_ref() or through g_type_create_instance() (this is being called by g_object_new()) or through one of the above done on a type derived from @new_type_id.

  3. This causes the type system to load the type's implementation by calling g_type_plugin_use() and g_type_plugin_complete_type_info() on @new_type_plugin.

  4. At some point the type's implementation isn't required anymore, e.g. after g_type_class_unref() or g_type_free_instance() (called when the reference count of an instance drops to zero).

  5. This causes the type system to throw away the information retrieved from g_type_plugin_complete_type_info() and then it calls g_type_plugin_unuse() on @new_type_plugin.

  6. 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 g_type_plugin_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 g_type_plugin_use() and g_type_plugin_complete_type_info() again when the type is needed again.

#GTypeModule 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.cr

Class Method Summary

Instance Method Summary

Class Method Detail

def self.g_type : UInt64 #

Instance Method Detail

def complete_interface_info(instance_type : UInt64, interface_type : UInt64, info : GObject::InterfaceInfo) : Nil #

def complete_type_info(g_type : UInt64, info : GObject::TypeInfo, value_table : GObject::TypeValueTable) : Nil #

abstract def to_unsafe #

def unuse : Nil #

def use : Nil #