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From: mheaney@ni.net (Matthew Heaney)
Subject: Re: Rules for Representation of Subtypes
Date: 1996/09/29
Message-ID: <mheaney-ya023180002909961030520001@news.ni.net>#1/1
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references: <mheaney-ya023080002209961353500001@news.ni.net>
 <1996Sep26.191257.1@eisner> <DyEr6p.38H@world.std.com>
 <1996Sep28.155354.1@eisner> <DyGwtp.Bs1@world.std.com>
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organization: Estormza Software
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newsgroups: comp.lang.ada
Date: 1996-09-29T00:00:00+00:00
List-Id: <comp.lang.ada>


In article <DyGwtp.Bs1@world.std.com>, bobduff@world.std.com (Robert A
Duff) wrote:

>In article <1996Sep28.155354.1@eisner>,
>Larry Kilgallen <kilgallen@eisner.decus.org> wrote:
>>If the assignment of the output causes erroneousness,
>>then why isn't the name of the operation Checked Conversion ?
>
>Heh?  If it were checked, it would do something sensible, like raise an
>exception, or return a well-defined result, or give a compile-time
>error.  The UNchecked means, it's *not* checked -- if you do something
>wrong, you get unpredictable behavior, i.e. erroneous execution.

I think his comment was in reaction a previous post, which stated that the
compiler would make all kinds of optimizations based on what it knew was an
illegal program as a result of a call to unchecked_conversion.  If the
compiler does something "special" to handle a "bad" program because of
unchecked_conversion, well, the conversion is not really "unchecked,"
right?

>- Bob

Matt

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Matthew Heaney
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mheaney@ni.net
(818) 985-1271