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From: "Jean-Pierre Rosen" <rosen.adalog@wanadoo.fr>
Subject: Re: Beware: Rep spec on an enumeration type causes code explosion
Date: 1997/12/10
Message-ID: <66mkr2$k0o$1@peuplier.wanadoo.fr>#1/1
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References: <gwinn-0812971210080001@dh5055133.res.ray.com>
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Organization: Adalog
Newsgroups: comp.lang.ada
Date: 1997-12-10T00:00:00+00:00
List-Id: <comp.lang.ada>



Tucker Taft wrote...
>So in retrospect, I believe enumeration representation
>clauses in Ada are a mistake.  If a user wants to name
>particular values, they should simply use named integer
>constants, or perhaps better, named private-type constants.  They can build
>up various maps of their own if they want to translate to/from some kind
>of "holey" representation from/to a contiguous representation.
>
An important issue is why is a representation clause necessary at all ?
In general, it is because of some interfaces to hardware or other
programming language. In this case, you can use an efficient representation
for internal use, and use a representation clause only for interfaces:

type Efficient_Enumeration is (...);
type External_Enumeration is new Efficient_Enumeration;
for External_Enumeration use (...);

You would convert to External_Enumeration (and incur some overhead) only
when needed.