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From: Andy <andy@nospam.com.tj>
Subject: Re: tagged types extensions - language design question
Date: 2000/01/29
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Date: 2000-01-29T09:01:47+00:00
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Vladimir Olensky wrote:
> Actually the problem is that naming scheme becomes more
> complicated as I need to invent names for such intermediate
> packages and everything should be clean and easily understandable.
> 

Although it is good practice to have each child class type in its
own package, if the intermediate type is just to allow a double
extension (one public, one private), why not just do so in the one
package, something like:

-- Root class
--
package P1 is

    type Root is abstract tagged null record;
    
    procedure Method (X : in Root) is abstract; 

end P1;


-- Child class
--
package P1.P2 is

    -- public extension
    -- this is abstract so we don't have to override any
   -- abstract operations defined by the paraent class.
   --
    type Intermediates is abstract new P1.Root with record
        F : Float;  -- etc.
    end record;

    type Objects is new Intermediates with private;

    procedure Method (X : in Objects);

private

    type Objects is new Intermediates with record
        I : Integer;  -- etc.
    end record;

end P1.P2;



Cheers
Andy