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From: bobduff@world.std.com (Robert A Duff)
Subject: Re: Valid Attribute and Unchecked Conversion
Date: 1996/10/04
Message-ID: <Dyr7Dt.HqL@world.std.com>#1/1
X-Deja-AN: 187518284
references: <DyCF97.7zp@world.std.com>
 <mheaney-ya023180000110962027510001@news.ni.net> <Dynt6I.5D1@world.std.com>
 <DyqAKA.DJn@thomsoft.com>
organization: The World Public Access UNIX, Brookline, MA
newsgroups: comp.lang.ada
Date: 1996-10-04T00:00:00+00:00
List-Id: <comp.lang.ada>


In article <DyqAKA.DJn@thomsoft.com>, Keith Thompson <kst@thomsoft.com> wrote:
>Are sparse enumeration types are really used all that much in real life?

They shouldn't be, because, as you explained, they don't work.  Using
sparse enums is asking for erroneousness.

Well, it's not *quite* that bad: You can use a sparse enum for sending
data from Ada to the outside world (e.g. doing output, passing
parameters *to* an imported subprogram, unchecked converting *from* a
sparse enum, etc).  But the other direction doesn't always work, and
should be avoided, IMHO.

The whole feature causes an awful lot of complexity in compilers,
given that it's not very useful.  Sigh.

- Bob