7. Memory management

GtkAda takes care of almost all the memory management for you. Here is a brief overview of how this works, you’ll have to check the sources if you want more detailed information. Gtk+ (the C library) does its own memory management through reference counting, i.e. any widget is destroyed when it is no longer referenced anywhere in the application.

In GtkAda itself, a ‘user_data’ is associated with each object allocated by a Gtk_New procedure. A ‘destroy’ callback is also associated, to be called when the object to which the user_data belongs is destroyed. Thus, every time a C object is destroyed, the equivalent Ada structure is also destroyed (see Gtk.Free_User_Data).

Concerning widgets containing children, every container holds a reference to its children, whose reference counting is thus different from 0 (and generally 1). When the container is destroyed, the reference of all its children and grand-children is decremented, and they are destroyed in turn if needed. So the deallocation of a widget hierarchy is also performed automatically.