From: mheaney@ni.net (Matthew Heaney)
Subject: Re: Valid Attribute and Unchecked Conversion
Date: 1996/10/02
Date: 1996-10-02T00:00:00+00:00 [thread overview]
Message-ID: <mheaney-ya023180000210962153160001@news.ni.net> (raw)
In-Reply-To: EACHUS.96Oct2161139@spectre.mitre.org
In article <EACHUS.96Oct2161139@spectre.mitre.org>,
eachus@spectre.mitre.org (Robert I. Eachus) wrote:
> declare
> type T is range 1 .. 10;
> for T'SIZE use Integer'SIZE;
> function To_T is new Unchecked_Conversion (Integer, T'Base);
> O : constant T := To_T (0);
> begin
> if O'Valid then
> ...
> end;
>
>Now To_T returns a bit pattern that is legal for the type (T'Base),
>and the constraint check occurs on the assignment. You never get to
>the call to O'Valid.
Thank you! That clears it up. I didn't realize that a Constraint_Check
ever could ever occur upon assignment of a value returned by an
instantiation of Unchecked_Conversion.
But your method forces a Constraint_Check to occur by making the type of
object O a subtype of the type returned by the function. (Technically,
makes the function return a supertype of O's type. Did I get that right?)
Very nice!
Matt
--------------------------------------------------------------------
Matthew Heaney
Software Development Consultant
mheaney@ni.net
(818) 985-1271
next prev parent reply other threads:[~1996-10-02 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 ` 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 ` 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 Dewar
1996-09-30 0:00 ` Matthew Heaney
1996-09-30 0:00 ` Robert A Duff
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 [this message]
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
1996-09-23 0:00 ` David C. Hoos, Sr.
1996-09-23 0:00 ` Samuel T. Harris
1996-09-26 0:00 ` David C. Hoos, Sr.
1996-09-23 0:00 ` Robert A Duff
1996-09-24 0:00 ` Robert Dewar
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
-- 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
replies disabled
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox