From: bobduff@world.std.com (Robert A Duff)
Subject: Re: Using the GNAT defined attribute: 'Enum_Rep
Date: 1997/09/08
Date: 1997-09-08T00:00:00+00:00 [thread overview]
Message-ID: <EG7Enp.3DF@world.std.com> (raw)
In-Reply-To: 340D6C5D.2E53@pseserv3.fw.hac.com
In article <340D6C5D.2E53@pseserv3.fw.hac.com>,
W. Wesley Groleau x4923 <wwgrol@pseserv3.fw.hac.com> wrote:
>... And in Ada 83, the above
>would not be legal because 'Size is _defined_ as non-static, thus
>can't be used to specify another 'Size.
S'Size is static if S is a static subtype (in both Ada 83 and 95).
>> 'Pos and 'Val. ... will work If and only if the representation is
>> identical to the position numbers - what you get if you don't
>> specify a representation. ....
>
>Is this true ?
Yes.
>... Seems to me it's legal (though I've never seen
>it happen) for an implementation to generate anything it wanted
>for a representation as long as ordering, indexing, etc. worked.
Yes, but 'Pos and 'Val still need to return what the RM says, which is
*not* based on the representation.
>I can imagine a CPU where a bit per value is more efficient, i.e.,
>an implicit
>
> for Enum use ( 0, 1, 2, 4, 8, 16, 32, ... );
Fine, but the 'Pos values are still 0, 1, 2, 3, ...
>though, again, I've never seen that done.
Me neither. We probably never will, either.
- Bob
next prev parent reply other threads:[~1997-09-08 0:00 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
1997-08-27 0:00 Using the GNAT defined attribute: 'Enum_Rep Marin David Condic, 561.796.8997, M/S 731-96
1997-09-03 0:00 ` W. Wesley Groleau x4923
1997-09-06 0:00 ` Robert Dewar
1997-09-08 0:00 ` W. Wesley Groleau x4923
1997-09-08 0:00 ` Matthew Heaney
1997-09-08 0:00 ` Robert A Duff
1997-09-08 0:00 ` Robert A Duff [this message]
1997-09-08 0:00 ` W. Wesley Groleau x4923
1997-09-08 0:00 ` Matthew Heaney
1997-09-09 0:00 ` Robert A Duff
1997-09-11 0:00 ` Robert Dewar
1997-09-08 0:00 ` Robert A Duff
-- strict thread matches above, loose matches on Subject: below --
1997-09-09 0:00 Marin David Condic, 561.796.8997, M/S 731-96
1997-09-09 0:00 ` W. Wesley Groleau x4923
1997-09-11 0:00 ` Robert Dewar
1997-09-09 0:00 Marin David Condic, 561.796.8997, M/S 731-96
1997-09-09 0:00 ` Robert A Duff
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