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Newsgroups: comp.lang.ada
Subject: Re: Generic Package
From: Georg Bauhaus <bauhaus@futureapps.de>
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Date: Thu, 26 Apr 2007 22:01:18 +0200
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Date: 2007-04-26T22:01:18+02:00
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On Thu, 2007-04-26 at 12:40 -0700, andrew.carroll@okstate.edu wrote:

> Who said anything about derivation?  Yeah, I used the word "is a" but
> that doesn't mean I want to build a whole class tree. 

Ah, OK.

>   So, is there a "Generic_Collection" type of package in Ada?

AFAIK, not in the sense that permits deciding the nature
of the collection at runtime, or based on the type parameter
(see also Dmitry's remarks).

IIRC, Matt Heaney had originally intended to re-export the
type T used as actual parameter for Element_Type of containers.
In this case you might have written Tuples.Element_Subtype
and instantiated other packages using this subtype without
naming T.

OTOH, the chaining is possible if I have understood correctly:

package Tuple is new Vectors(Element_Type => attribute, ...);

package Table is new Hashed_Sets(Element_Type => Tuple.Vector, ...);