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From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: Re: GTK and tasking (GNAT)
Date: Sat, 03 May 2014 22:23:01 +0100
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Date: 2014-05-03T22:23:01+01:00
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hreba <hreba@terra.com.br> writes:

>             accept StartCounter (txtBox: Gtk.GEntry.Gtk_Entry) do
>                for i in 1..10 loop
>                   Gtk.GEntry.Set_Text (txtBox, Integer'Image(i));
>                   Gtk.Widget.Queue_Draw (Gtk.Widget.Gtk_Widget(txtBox));
>                   delay 0.5;
>                end loop;
>             end StartCounter;

The calling task (probably the Gtk main loop) blocks while the body of
the accept statement is executed.

I don't know how this ought to be done in Gtk, though I strongly suspect
it's not like that! However, the way to deal with the task problem would
normally be to save the values passed with the accept and deal with them
afterward:

   accept StartCounter (txtBox: Gtk.GEntry.Gtk_Entry) do
      txtBoxCopy := txtBox;
   end StartCounter;
   --  Now the caller can carry on while we work with the passed value.
   for i in 1..10 loop
      Gtk.GEntry.Set_Text (txtBoxCopy, Integer'Image(i));
      Gtk.Widget.Queue_Draw (Gtk.Widget.Gtk_Widget(txtBoxCopy));
      delay 0.5;
   end loop;

Questions: is Gtk thread-safe? is Queue_Draw something that should only
be called from the Gtk event queue?