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From: Matthew Heaney <matthew_heaney@acm.org>
Subject: Re: Generic child unit renaiming
Date: 1999/04/25
Message-ID: <m3vhekmjcj.fsf@mheaney.ni.net>#1/1
X-Deja-AN: 470821663
References: <7fn4vg$298$1@ilana.cenaath.cena.dgac.fr>
NNTP-Posting-Date: Sun, 25 Apr 1999 15:17:25 PDT
Newsgroups: comp.lang.ada
Date: 1999-04-25T00:00:00+00:00
List-Id: <comp.lang.ada>

noiraud@cenaath.cena.dgac.fr writes:

> I would like to rename Math_Extension an extension of the
> generic package Ada.Numerics.Generic_Elementary_Functions.

Don't do this.

> An other solution could be to implement in Math_Extension package using an
> instanciation of Generic_Elementary_Functions :
> 
>    generic
>       type Real is digits <>;
>    package Math_Extension is
> 
>       package Math is new Ada.Numerics.Generic_Elementary_Functions (Real);
> 
>       function Sqrt (X : Real'Base) return Real'Base renames Math.Sqrt;
> 
>       ...
> 
>       function Log10 (X : Real'Base) return Real'Base;
> 
>       function Asin  (X : Real'Base) return Real'Base
>          renames Math.Arcsin;
> 
>    end Math_Extension;
> 
> but instanciate Math_Extension has a performance cost because of the double
> instanciation.


I don't know what you mean by "performance cost," but you can always
import the instantiation as a generic formal package:

with Ada.Numerics.Generic_Elementary_Functions; use Ada.Numerics;
generic
  type Real is digits <>;
  with package Math is new Generic_Elementary_Functions (Real);
package Math_Extension is ...;