From: dewar@gnat.com
Subject: Re: Alternate to Unchecked_Conversion - Portable?
Date: 1999/03/01
Date: 1999-03-01T00:00:00+00:00 [thread overview]
Message-ID: <7bei3a$pjk$1@nnrp1.dejanews.com> (raw)
In-Reply-To: 7be1ot$mjg$1@plug.news.pipex.net
In article <7be1ot$mjg$1@plug.news.pipex.net>,
"Nick Roberts" <Nick.Roberts@dial.pipex.com> wrote:
> But, we (programmers in the real world) also need to do
> what we can to punish compiler makers whose products: (a)
> fail to conform to the standard;
> (b) conform, but in a way that is likely to create
> portability difficulties (without good excuse). Even if
> this is just in the form of disrecommendation to clients
> (I am a consultant) or colleagues, we need to stand
> shoulder-to-shoulder.
It's not so simple. Conformance to the standard is a
desirable property, but not the only desirable property,
and a compiler vendor who considers conformance to be
of primary importance over all other considerations may
well produce a very correct compiler that is not however
usable for any number of reasons (just remember that Ada/Ed
was fully conformant :-)
To take a simple example, an x86 compiler that does not
support 80-bit IEEE extended arithmetic is clearly violates
B.2(10):
10 Floating point types corresponding to each floating
point format fully supported by the hardware.
and is thus non-conformant. It will still be fully
validatable, since this is not the sort of thing the
validation can test with automated tests.
Does that mean the compiler is unusable, or we should
recommend that people not use it? Seems an extreme
viewpoint to me. If your application does not need 80-bit
float (or perhaps even does not want it, since it wants to
be completely portable), then this omission may be
completely unimportant.
Robert Dewar
Ada Core Technologies
P.S. Just to ensure that people do not regard the above as
special pleading for non-conformances in GNAT, please be
sure to realize that GNAT *does* support 80-bit float on
the ia32 (x86).
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next prev parent reply other threads:[~1999-03-01 0:00 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
1999-02-21 0:00 Alternate to Unchecked_Conversion - Portable? Steve Doiel
1999-02-21 0:00 ` Steve Quinlan
1999-02-22 0:00 ` robert_dewar
1999-02-21 0:00 ` Matthew Heaney
1999-02-22 0:00 ` Christopher Green
1999-02-23 0:00 ` Matthew Heaney
1999-02-23 0:00 ` Samuel Mize
1999-02-24 0:00 ` robert_dewar
1999-02-25 0:00 ` Nick Roberts
1999-02-25 0:00 ` robert_dewar
1999-02-26 0:00 ` Nick Roberts
1999-02-26 0:00 ` Matthew Heaney
1999-02-27 0:00 ` Nick Roberts
1999-02-24 0:00 ` robert_dewar
1999-02-23 0:00 ` Christopher Green
1999-02-25 0:00 ` robert_dewar
1999-02-24 0:00 ` Christopher Green
1999-02-25 0:00 ` robert_dewar
1999-02-25 0:00 ` dennison
1999-02-25 0:00 ` Christopher Green
1999-02-26 0:00 ` Tom Moran
1999-02-26 0:00 ` robert_dewar
1999-02-26 0:00 ` robert_dewar
1999-02-26 0:00 ` Christopher Green
1999-03-01 0:00 ` Nick Roberts
1999-03-01 0:00 ` dewar [this message]
1999-03-01 0:00 ` Nick Roberts
1999-02-26 0:00 ` Robert A Duff
1999-02-28 0:00 ` robert_dewar
1999-02-23 0:00 ` Christopher Green
1999-02-25 0:00 ` robert_dewar
1999-02-24 0:00 ` Christopher Green
1999-02-25 0:00 ` robert_dewar
1999-02-26 0:00 ` Dale Stanbrough
1999-02-26 0:00 ` Robert A Duff
1999-02-22 0:00 ` robert_dewar
1999-02-22 0:00 ` Samuel Mize
1999-02-22 0:00 ` Tom Moran
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