RE: Pascal's: Variant Record or C's union

["Beard, Frank" <beardf@spawar.navy.mil>]

It's very similar to Pascal.

type Type_Of_Goods is (LIQUID, TEXTILE);

type TYPE_GOODS (GOODS_TYPE : Type_Of_Goods) is
  record
    ITEM_NAME : string(1..6);
    case GOODS_TYPE is
       when LIQUID =>
                  LITRE : float;
                  VOLUME_PCT : float;
       when TEXTILE =>
                  LENGTH : float;
                  WIDTH : float;
    end case;
  end record;

Frank


-----Original Message-----
From: Frank [mailto:franjoe@frisurf.no]
Sent: Friday, April 06, 2001 5:48 PM
To: comp.lang.ada@ada.eu.org
Subject: Pascal's: Variant Record or C's union


Hi!

How do I create a record in Ada, that behaves as the variant record in
Pascal or similar to the union in C?
It seems to me that the expression "variant" in Ada is used on how you
define?/declare? :-) types based on a "type with many possible
apperances":-).

Something like:

type TYPE_GOODS is
  record
    ITEM_NAME : string(1..6);
    GOODS_TYPE : integer;
    case GOODS_TYPE <--------???
       when LIQUID:        <---------???
                  LITRE : float;
                  VOLUME_PCT : float;
       when TEXTILE:
                  LENGTH : float;
                  WIDTH : float;
    end case;
  end record;


A : TYPE_GOODS;
..
..
A.ITEM_NAME := 'COGNAC';
A.GOODS_TYPE := LIQUID;
A.LITRE := 0.7;
A.VOLUME_PCT := 45;

A.ITEM_NAME := 'RED   ';
A.GOODS_TYPE := TEXTILE;
A.LENGTH := 10.0;
A.WIDTH := 0.6;




Frank


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