From: mheaney@ni.net (Matthew Heaney)
Subject: Valid Attribute and Unchecked Conversion
Date: 1996/10/01
Date: 1996-10-01T00:00:00+00:00 [thread overview]
Message-ID: <mheaney-ya023180000110962027510001@news.ni.net> (raw)
In-Reply-To: qw6buemy9ea.fsf@gargantua.enst.fr
In article <qw6buemy9ea.fsf@gargantua.enst.fr>, Samuel Tardieu
<sam@ada.eu.org> wrote:
>I don't think that the Valid attribute has been put in the language to
>be used after an Unchecked_Conversion, but rather to be used after
>calls to imported subprograms and calls to Read attributes (data
>coming from a stream).
That's odd, because RM95, section 13.9.2 states that "The valid attribute
can be used to check the validity of data produced by unchecked
conversion,..."
Note 19 in that section (of the AARM) states that "invalid data" can be
created as "the result of unchecked conversion."
Note 20 states that since X'Valid is not considered a read of X, it is not
an error the check the validity of invalid data.
So it's legal to check (using the valid attribute) the value of a (scalar)
object with an invalid representation, right?
Given the following program:
declare
type T is range 1 .. 10;
function To_T is new Unchecked_Conversion (Integer, T);
O : constant T := To_T (0);
begin
if O'Valid then
...
end;
I want to know if the program is correct. Is it erroneous, yes or no?
--------------------------------------------------------------------
Matthew Heaney
Software Development Consultant
mheaney@ni.net
(818) 985-1271
next prev parent reply other threads:[~1996-10-01 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 A Duff
1996-09-27 0:00 ` Robert Dewar
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 ` Robert A Duff
1996-10-01 0:00 ` Samuel Tardieu
1996-10-01 0:00 ` Matthew Heaney [this message]
1996-10-02 0:00 ` Valid Attribute and Unchecked Conversion Robert A Duff
1996-10-04 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
1996-10-04 0:00 ` Matthew Heaney
1996-10-07 0:00 ` Robert Dewar
1996-10-09 0:00 ` Keith Thompson
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
1996-10-07 0:00 ` Kenneth Almquist
1996-10-01 0:00 ` Rules for Representation of Subtypes Ken Garlington
1996-09-28 0:00 ` Larry Kilgallen
1996-09-29 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
1996-09-29 0:00 ` Matthew Heaney
1996-09-30 0:00 ` Robert A Duff
1996-09-30 0:00 ` Robert Dewar
1996-09-30 0:00 ` Matthew Heaney
1996-10-03 0:00 ` Robert Dewar
1996-10-02 0:00 ` Valid Attribute and Unchecked Conversion Robert I. Eachus
1996-10-02 0:00 ` Matthew Heaney
1996-10-02 0:00 ` 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
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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