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From: Henri Delebecque <delebecq@supelec.fr>
Subject: problem with polymorphism
Date: 1997/11/20
Message-ID: <651n1d$e7p@prof.ese-metz.fr>#1/1
X-Deja-AN: 291035783
X-XXMessage-ID: <B09A1F5E48026405@delebecque.supelec.fr>
Distribution: world
Organization: Supelec
Newsgroups: comp.lang.ada
Date: 1997-11-20T00:00:00+00:00
List-Id: <comp.lang.ada>


Hello,

I'm currently evaluating tagged types in Ada95, and encounter some
problems
with the following code:

type Point is tagged record
        x : integer := 0;
        y : integer := 0;
end record;
type Point3D is new Point with record
        z : integer := 0;
end record;
procedure print (unPoint : in Point) is
begin
        put ("Point:[");
	...
end print;
procedure print (unPoint3D : in Point3D) is
begin
...
end print;
procedure printing (unPoint : in Point'Class) is
begin
        print(unPoint);
end printing;

gnat's error message is
testpoly.adb:40:17: class-wide argument not allowed here
testpoly.adb:40:17: "imprime" is not a primitive operation of "Point"

Please, could someone helps me ?
Thanks
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| Henri Delebecque                        delebecq@supelec.fr |
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