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:

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.

2. The type's implementation is referenced, e.g. through GObject::TypeClass#ref or through GObject::type_create_instance (this is being called by GObject::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 GObject::TypePlugin#use and GObject::TypePlugin#complete_type_info on new_type_plugin.

4. At some point the type's implementation isn't required anymore, e.g. after GObject::TypeClass#unref or GObject::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 GObject::TypePlugin#complete_type_info and then it calls GObject::TypePlugin#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 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

• Gio::IOModule
• GObject::TypeModule

Defined in:

lib/gi-crystal/src/auto/g_object-2.0/type_plugin.cr

Constructors

• .cast(obj : GObject::Object) : self

  Cast a GObject::Object to self, throws a TypeCastError if the cast can't be made.

Class Method Summary

• .cast?(obj : GObject::Object) : self | Nil
• .g_type : UInt64

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

Constructor Detail

Class Method Detail

Instance Method Detail