Re: Access check failed

[Stephen Leake <stephen_leake@acm.org>]

gilmour@banda.lv (gilmour) writes:

> Why when I press 'Insert' button, following error appears?
> "CONSTRAINT_ERROR: win_new_employee_pkg.ads:25 access check failed"
> I'am using GtkAda-2.2.0

>    procedure On_Btninsert_Pressed(Object : access Gtk_Button_Record'Class)is
> 
>    begin
> 
>       Set_Text(win_new_employee.entry3, "");

This is referencing Win_New_Employee_Pkg.Win_New_Employee, which is
never set, so it is null, so you get an access check failure.

You need to get the parent of the parent of Object; that is the top
level window containing Entry3.

>    end On_Btninsert_Pressed;
> 
> end Win_New_Employee_Pkg.Callbacks;

> procedure Gtk_New (Win_New_Employee : out Win_New_Employee_Access) is
> begin
>    Win_New_Employee := new Win_New_Employee_Record;

This is the out parameter Win_New_Employee, _not_ the global
Win_New_Employee_Pkg.Win_New_Employee.

>    Win_New_Employee_Pkg.Initialize (Win_New_Employee);
> end Gtk_New;
> 

Here is a typical event handler from one of my applications:

procedure On_Enabled_Clicked (Button : access Gtk.Button.Gtk_Button_Record'Class)
is
  Check_Button : constant Gtk.Check_Button.Gtk_Check_Button := Gtk.Check_Button.Gtk_Check_Button (Button);
  View         : constant Gtk_View                          := Gtk_View (Gtk.Button.Get_Parent (Button));
begin
  View.Data.Enabled := Gtk.Check_Button.Get_Active (Check_Button);
end On_Enabled_Clicked;

Hope this helps.

There is also a GtkAda mailing list; see http://libre.act-europe.fr/

-- 
-- Stephe