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From: "Matthew Heaney" <mheaney@on2.com>
Newsgroups: comp.lang.ada
Subject: Re: Integers and Mathematical Correctness
Date: Wed, 31 Oct 2001 18:16:14 -0500
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Date: 2001-10-31T18:16:14-05:00
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"chris.danx" <chris.danx@ntlworld.com> wrote in message
news:Ij%D7.47224$a14.5418893@news6-win.server.ntlworld.com...
> So when a new integer type is declared, a group of operators are created
for
> that type but their behaviour can be still be changed?  Ok, I get it now!

Yes.  This is the same inheritance model like any other OO language.  In
general:

package P is

   type T is <whatever>;
   procedure Op (O : T);
...
end P;

package Q is
   type NT is new T;
end;

At the point of declaration of Q.NT, operation Q.Op is implicitly declared.

It doesn't matter that the parent type in your example was
Standard.Integer -- the model is the same.  Primitive operations of the
parent type are inherited by the derived type.

In the case of predefined types, you can "squirral away" (ha ha, Bob) a
predefined operator prior to overriding it:

package Q is
   type My_Integer is new Integer;
   function Predefined_Div (L, R: My_Integer) return My_Integer renames "/";
   function "/" (L, R : My_Integer) return My_Integer; --override
end;

The saves you the trouble of having to convert back to the parent type in
the body, when you need the predefined behavior (here, for division).