[gtkada] Gtk & Genericity

[Frederic Gobry]

Hi,

For teaching purposes, I try to build some generic packages for
manipulating generic data structures from a Gtk interface. My idea is
to have a generic package, let's call it Relations, which has a child
unit Relations.Edition containing primitives for UI manipulation. I
only want to provide simple high level functions in it, like Display
and Edit, and hide all the internal methods needed for Gtk (esp.
callbacks).

But I can't compile the enclosed code, due to genericity problems. Is
there a workaround for that ?

> gnatmake test_gen.adb `gtkada-config`
gcc -c -I/opt/gnat/include/gtkada test_gen.adb
simple_gen.adb:12:04: instantiation error at gtk-marshallers.ads:359
simple_gen.adb:12:04: instantiation error at gtk-handlers.ads:437
simple_gen.adb:12:04: parent type must not be outside generic body

Thanks for your help...

Frédéric

-- 
  Frédéric GOBRY
       	       	       	      EPFL
Research Assistant     CH 1015 - Lausanne
   GRIP - LITH       Tel: +41 21 693 66 92
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with Gtk; use Gtk;
with Gtk.Main; use Gtk.Main;
with Gtk.Widget; use Gtk.Widget;
with Gtk.Window; use Gtk.Window;
with Ada.Text_Io; use Ada.Text_Io;
with Gdk.Event; use Gdk.Event;
with Gtk.Button; use Gtk.Button;
with Gtk.Handlers; use Gtk.Handlers;

package body Simple_Gen is

   package Button_Callback is new
     Gtk.Handlers.Callback
     (Widget_Type => Gtk_Button_Record);

   procedure Close_Window (Button : access Gtk_Button_Record'Class) is
   begin
      Destroy(Get_Toplevel (Button));
      Gtk.Main.Main_Quit;
   end Close_window;

   procedure Display(Text : String) is
      Window : Gtk_Window;
      Button : Gtk_Button;
   begin
      Gtk.Main.Init;
      Gtk_New (Window);
      Gtk_New (Button,"test");
      Add (Window, Button);

      Button_Callback.Connect (Button, "clicked",
                               Button_Callback.To_Marshaller (Close_Window'Access));

      Set_Usize(Window,50,50);
      Set_Title(Window,Text);

      Show_all(Window);
      Gtk.Main.Main;

   end Display;

end Simple_gen;
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generic
package Simple_gen is

   procedure Display(Text : String);

end Simple_gen;
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with Simple_Gen;

procedure Test_Gen is

   package Gen is new Simple_Gen;

begin

   Gen.Display ("hey !");

end;