[gtkada] How to connect a button Handler to a task entry?

[Dmitry A. Kazakov]

On Thu, 13 May 2010 01:48:02 +0100, you wrote:

> I am currently learning Gtkada and Ada in general at the moment. I am been
> trying to find an example on how to connect a button event to a task entry
> but have failed so far. Could anyone please show me a simple example of
> the handler syntax declaration and the .connect?

You should wrap the entry call into a procedure. E.g.:

   task type Handler is
      entry Click;
   end Handler;
   type Handler_Ptr is access all Handler;

   package Entry_Handlers is
      new Gtk.Handlers.User_Callback (Gtk_Widget_Record, Handler_Ptr);

   procedure Clicked
      (Widget : access Gtk_Widget_Record'Class; Ptr : Handler_Ptr) is
   begin
       Ptr.Click;
   end Clicked;
...
   Listener : aliased Handler;
...
   Entry_Handlers.Connect
   (  Button,
      "clicked",
      Clicked'Access,
      Listener'Access
   );

However I would never do this. An entry call is blocking, if the task you
call is not ready for the rendezvous. That will freeze the GUI. Then you
cannot do [at least directly] any GTK calls from the task. So it is rather
useless.

If you want to communicate with a task from a GTK event, use a protected
object instead.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de