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From: Ken Garlington <garlingtonke@lmtas.lmco.com>
Subject: Re: Valid Attribute and Unchecked Conversion
Date: 1996/10/07
Message-ID: <3258EADB.45D2@lmtas.lmco.com>#1/1
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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>
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organization: Lockheed Martin Tactical Aircraft Systems
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Date: 1996-10-07T00:00:00+00:00
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Robert A Duff wrote:
> 
> 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.

Or, you can do an unchecked conversion to a record with a single
component of the sparse enum type, right?

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

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