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From: Nick Roberts <nick.roberts@acm.org>
Newsgroups: comp.lang.ada
Subject: Re: Accessing the underlying rep for enumerated types?
Date: Wed, 13 Oct 2004 22:49:46 +0100
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Date: 2004-10-13T22:49:46+01:00
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Dale Stanbrough wrote:

> <sigh>....

Yes, me too. The answers to Dale's question seem to have been a little
less than courteous and sympathetic.

> Obviously I have to phrase this much more pedantically.
> 
> Is there any feature in the language that allows me to get access
> to the underlying enumeration values other than using Unchecked
> Conversion?

I think the answer is "No", there is no such feature in the language.

Obviously any use of Unchecked_Conversion is theoretically non-portable,
and so, indeed, is any attempt to specify the representation of an
enumerated type.

On the other hand, I suspect that using Unchecked_Conversion to convert
to a modular type of the right size is likely to work on most
implementations (perhaps all that don't reject it). I've tested this
with GNAT 3.15p (it works). Writing out a value of the enumerated type
to a stream, and then reading it back into an object of a modular type
(of the right size) might also work.

Some implementations might provide an attribute which returns the
underlying value. I admit, I'm not aware of any.

-- 
Nick Roberts