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From: dewar@schonberg.cs.nyu.edu (Robert Dewar)
Subject: Re: Valid Attribute and Unchecked Conversion
Date: 1996/10/07
Message-ID: <dewar.844696412@schonberg>#1/1
X-Deja-AN: 187328731
references: <DyCF97.7zp@world.std.com>
 <mheaney-ya023180000110962027510001@news.ni.net> <Dynt6I.5D1@world.std.com>
 <DyqAKA.DJn@thomsoft.com> <Dyr7Dt.HqL@world.std.com>
 <DyuCzu.29G@thomsoft.com>
organization: New York University
newsgroups: comp.lang.ada
Date: 1996-10-07T00:00:00+00:00
List-Id: <comp.lang.ada>


Keith says

"For example, the language could have defined two additional attributes,
analagous to 'Pos and 'Val, but operating on the internal representation
of an enumeration type.  If the argument is an invalid representation,
simply raise Constraint_Error.  GNAT provides half of this with its
'Enum_Rep attribute."


The intention in Ada 95 is that both operations are achievbable using
unchecked conversion. It is a bug in the RM if this is not the case.

However, in practice, of coruse this works, no matter what it says in
the RM, so this point can be left moot without having any pragmatic 
effect.