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From: Roland Illig <roland.illig@gmx.de>
Newsgroups: comp.lang.ada
Subject: Re: [newbie] simple(?) data structures
Date: Wed, 16 Jun 2004 13:08:41 +0200
Message-ID: <2jao1qFvj2rgU1@uni-berlin.de>
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Date: 2004-06-16T13:08:41+02:00
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Roland Illig wrote:
> Hi,
> 
> I'm doing my first steps with Ada. I tried to model a Go board and 
> failed. In Java/C++, I would do it like this:
> 
> enum Stone { Empty, Black, White };
> 
> class Go_Board {
 > ...
> }
> 
> How can I do this in Ada? I already tried something with packages and 
> generics, but that did not look nice. But I want it to look nice and 
> Adaish.

Many thanks for all your help. As I'm just an Ada beginner, I'll stick 
to something simple. No packages, no inheritance. Perhaps it will evolve 
later. My first try is:

with Ada.Finalization;

package Go is

    type Stone is (Empty, Black, White);

    type Player is (Black, White);
    Other : constant array (Player) of Player := (Black => White, White 
=> Black);
    To_Stone : constant array (Player) of Stone := (Black => Black, 
White => White);

    type Move is private;
    Pass_Move : constant Move;

    type Board (Size : Positive) is private;
    function Get_Stone (The_Board : Board; X, Y : Positive) return Stone;
    procedure Do_Move (The_Board : in out Board; The_Move : in Move);
    -- ...

private

    type Move is
       record
          Pass : Boolean := False;
          X, Y : Positive;
       end record;
    Pass_Move : constant Move := (Pass => True, X => 1, Y => 1);

    type Stone_Array is array (Positive range <>, Positive range <>) of 
Stone;
    type Stone_Array_Access is access Stone_Array;
    type Board (Size : Positive) is new Ada.Finalization.Controlled with
       record
          The_Size : Natural := Size;
          Current_Player : Player := Black;
          Stones : Stone_Array_Access;
       end record;
    procedure Initialize(The_Board : in out Board);
    procedure Finalize(The_Board : in out Board);

end Go;

-- Roland