Re: Help needed: Access type to functions in generic package

["Matthew Heaney" <matthew_heaney@acm.org>]

In article <37DBA86F.3805AA69@deathsdoor.com> , Zeiram 
<zeiram@deathsdoor.com>  wrote:


> generic
>     Dim_X, Dim_Y, Dim_Z : Positive;
> package Maze is
>     type T_Cell is (Wall, Corridor, Pebble);
>     type T_Maze is array(1..Dim_X, 1..Dim_Y, 1..Dim_Z) of T_Cell;
> end Maze;

Why is this package generic?  Why don't you declare your array type this
way:

package Maze is

  type T_Cell is (Well, Corridor, Pebble);

  type T_Maze is
    array (Positive range <>, Positive range <>, Positive range <>)
    of T_Cell;

end Maze;


Instead of instantiating a generic to get a constrained array subtype, you
can just declare an array object, or declare an array subtype.  No generic
is needed.

  Maze : T_Maze (1 .. 10, 2 .. 11, 3 .. 12);

or

  subtype My_Maze is T_Maze (1 .. 10, 2 .. 11, 3 .. 12);

  Maze : My_Maze;




> generic
> package Maze.Display is
>     procedure Display_Maze(Maze : in T_Maze);
> end Maze.Display;

I package Maze is non-generic, then this child package doesn't need to be
generic either:

  package Maze.Display is

    procedure Display_Maze (Maze : in T_Maze);
    -- (sub)type T_Maze is now an unconstrained array

  end;



> with glut;
> with Win32.GL;
> with Maze.Display.Callback;
> package body Maze.Display is
>     package Callback is new Maze.Display.Callback;
>     use Callback;


Maze.Display.Callback doesn't need to be generic; see below.


>     procedure Display_Maze(Maze : in T_Maze) is
>       Menu : Integer;
>     begin
>       Menu := glutCreateMenu(Main_Menu'access);
>     end Display_Maze;
>
> end Maze.Display;
>
> package Maze.Display.Callback is
>     procedure Main_Menu(Value : Integer);
> end Maze.Display.Callback;


Again, this doesn't need to be generic either:

  package Maze.Display.Callback is

    procedure Main_Menu (...);

  end Maze.Display.Callback;


Try the changes I've suggested, and see if your problem goes away.