From: bobduff@world.std.com (Robert A Duff)
Subject: Re: Valid Attribute and Unchecked Conversion
Date: 1996/10/14
Date: 1996-10-14T00:00:00+00:00 [thread overview]
Message-ID: <Dz8oLE.KuB@world.std.com> (raw)
In-Reply-To: Dyvo0w.7Dr@thomsoft.com
In article <Dyvo0w.7Dr@thomsoft.com>, Keith Thompson <kst@thomsoft.com> wrote:
>But RM95-13.9.1(12) says:
> A call to an imported function or an instance of
> Unchecked_Conversion is erroneous if the result
> is scalar, and the result object has an invalid
> representation.
>
>Probably that paragraph should have been in 13.9 rather than 13.9.1.
True.
>Note that there are several paragraphs after this in the AARM encouraging
>implementations to behave sensibly:
>
> [...] We considered requiring such sensible behavior,
> but it resulted in too much arcane verbiage, and
> since implementations have little incentive to behave
> irrationally, such verbiage is not important to have.
>
>So implementations are encouraged to implement sensibly something that
>users are encouraged to avoid.
No, no. The "sensible" comment in the AARM is *not* referring to the
paragraph about erroneousness of unchecked conversions. It is referring
to the run-time behavior of "invalid" values, which can arise from many
things, but mainly uninitialized variables. The intent is that (for
example):
if X = Red and X /= Red then ...
should be True, despite the fact that X is not initialized (assuming the
compiler fails to catch the bounded error, and raise an exception).
This has nothing to do with the erroneousness defined in paragarph 12,
which would have been clearer if the AARM comment were after paragraph
11, rather than after paragraph 12.
- Bob
next prev parent reply other threads:[~1996-10-14 0:00 UTC|newest]
Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top
1996-09-22 0:00 Rules for Representation of Subtypes Matthew Heaney
1996-09-23 0:00 ` David C. Hoos, Sr.
1996-09-23 0:00 ` Robert A Duff
1996-09-23 0:00 ` Samuel T. Harris
1996-09-26 0:00 ` David C. Hoos, Sr.
1996-09-24 0:00 ` Robert Dewar
1996-09-26 0:00 ` Keith Thompson
1996-09-26 0:00 ` Matthew Heaney
1996-09-27 0:00 ` Robert Dewar
1996-09-27 0:00 ` Robert A Duff
1996-09-27 0:00 ` Robert Dewar
1996-09-27 0:00 ` Robert A Duff
1996-09-24 0:00 ` Robert Dewar
1996-09-23 0:00 ` Robert A Duff
1996-09-24 0:00 ` Matthew Heaney
1996-09-26 0:00 ` Robert A Duff
1996-09-26 0:00 ` Larry Kilgallen
1996-09-27 0:00 ` Robert A Duff
1996-09-27 0:00 ` Mark A Biggar
1996-09-30 0:00 ` Robert A Duff
1996-10-01 0:00 ` Larry Kilgallen
1996-10-01 0:00 ` Samuel Tardieu
1996-10-01 0:00 ` Ken Garlington
1996-10-01 0:00 ` Valid Attribute and Unchecked Conversion Matthew Heaney
1996-10-02 0:00 ` Robert A Duff
1996-10-04 0:00 ` Keith Thompson
1996-10-04 0:00 ` Matthew Heaney
1996-10-07 0:00 ` Robert Dewar
1996-10-09 0:00 ` Keith Thompson
1996-10-04 0:00 ` Robert A Duff
1996-10-04 0:00 ` Robert Dewar
1996-10-11 0:00 ` Norman H. Cohen
1996-10-12 0:00 ` Robert Dewar
1996-10-06 0:00 ` Keith Thompson
1996-10-07 0:00 ` Robert Dewar
1996-10-09 0:00 ` Keith Thompson
1996-10-07 0:00 ` Ken Garlington
1996-10-08 0:00 ` Alan Brain
1996-10-07 0:00 ` Kenneth Almquist
1996-10-07 0:00 ` Robert Dewar
1996-10-10 0:00 ` Ken Garlington
1996-10-11 0:00 ` Robert Dewar
1996-10-14 0:00 ` Keith Thompson
1996-10-14 0:00 ` Ken Garlington
1996-10-01 0:00 ` Rules for Representation of Subtypes Robert A Duff
1996-09-28 0:00 ` Larry Kilgallen
1996-09-29 0:00 ` Robert A Duff
1996-09-29 0:00 ` Matthew Heaney
1996-09-30 0:00 ` Robert Dewar
1996-09-30 0:00 ` Matthew Heaney
1996-09-30 0:00 ` Robert A Duff
1996-09-29 0:00 ` Larry Kilgallen
1996-09-29 0:00 ` Matthew Heaney
1996-09-30 0:00 ` Robert A Duff
1996-10-01 0:00 ` Ken Garlington
1996-10-02 0:00 ` Robert A Duff
1996-10-02 0:00 ` Ken Garlington
1996-10-06 0:00 ` Robert Dewar
1996-10-03 0:00 ` Robert Dewar
1996-10-02 0:00 ` Valid Attribute and Unchecked Conversion George Haddad
1996-10-03 0:00 ` John Herro
1996-10-04 0:00 ` Karl Cooper {46901}
1996-10-07 0:00 ` Mark A Biggar
1996-10-08 0:00 ` Robert Dewar
1996-10-05 0:00 ` Robert Dewar
1996-10-06 0:00 ` Keith Thompson
1996-10-14 0:00 ` Robert A Duff [this message]
1996-10-02 0:00 ` Robert I. Eachus
1996-10-02 0:00 ` Matthew Heaney
1996-09-27 0:00 ` Rules for Representation of Subtypes Matthew Heaney
1996-09-27 0:00 ` Robert A Duff
-- strict thread matches above, loose matches on Subject: below --
1996-10-03 0:00 Valid Attribute and Unchecked Conversion Franco Mazzanti
1996-10-04 0:00 Franco Mazzanti
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