Re: [sv-ac] call to vote on 1549

Hi Shalom:

Lisa and I had a discussion yesterday about the example in the 1549
proposal.

I do not think the LRM as it stands now allows $ to be assigned to a
variable or passed as actual argument expression to a typed formal
argument.  Do you know otherwise?

The main conceptual issue that I see with allowing $ to be assigned to
a variable or passed as actual argument expression to a typed formal
argument is defining what value it has in the space of possible values
for the associated data type.

It doesn't seem quite right to me to say that if $ is assigned to a
shortint, for example, then the value is the largest one that can be
represented in an shortint.  On the other hand, maybe this is a useful
and sensible definition.  With definitions of this kind, the meaning
of $ is dependent on the data type into which it is assigned or to
which it is bound, but there is already precedent for that in the
various coercion rules.

I recommended that we avoid this problem altogether for now and not
allow $ to be assigned to a variable or passed as actual argument
expression to a typed formal argument.  I recommended that Lisa change
the example to pass $ to a context formal argument.

J.H.

> X-Authentication-Warning: server.eda-stds.org: majordom set sender to owner-sv-ac@eda.org using -f
> X-ExtLoop1: 1
> X-IronPort-AV: E=Sophos;i="4.19,269,1183359600"; 
>    d="scan'208";a="118117813"
> X-MIMEOLE: Produced By Microsoft Exchange V6.5
> Content-class: urn:content-classes:message
> Date: Thu, 16 Aug 2007 09:15:58 +0300
> X-MS-Has-Attach: 
> X-MS-TNEF-Correlator: 
> Thread-Topic: [sv-ac] call to vote on 1549
> Thread-Index: AcfeiQ52OKcMoqhRQC+dKxDIPbJwOwADZVDwABotlYAAMwPDUA==
> From: "Bresticker, Shalom" <shalom.bresticker@intel.com>
> Cc: <sv-ac@eda-stds.org>
> X-OriginalArrivalTime: 16 Aug 2007 06:15:59.0713 (UTC) FILETIME=[EA184510:01C7DFCC]
> X-eda.org-MailScanner: Found to be clean, Found to be clean
> X-Spam-Status: No, No
> X-MIME-Autoconverted: from quoted-printable to 8bit by server.eda-stds.org id l7G6GDdJ019035
> Sender: owner-sv-ac@eda.org
> X-eda.org-MailScanner-Information: Please contact the ISP for more information
> X-eda.org-MailScanner-From: owner-sv-ac@server.eda.org
> 
> The LRM states in other places restrictions on the use of $. 
> The question is whether the example fulfills those conditions.
> 
> The following quoted wording is a little unclear: 
> 
> > An actual argument can replace any of the following:
> > - Identifier
> > - Expression
> > - Event control expression
> > - Upper delay range or repetition range if the actual argument is $
> 
> "can replace" seems a little problematic here.
> An actual argument cannot really replace an expression. E.g., it cannot
> replace a+b. It can replace a formal argument which is used as an
> expression, which is a little different.
> 
> And does this list cover all the possibilities, or is it just intended
> to be examples?
> 
> And does the last item mean:
> 1. If the actual argument is $, it can be used only in this way? If it
> is not $, can it be used in this way?
> 2. It can be used in this way only if it is $? If it is $, can it be
> used in another way?
> 
> Thanks,
> Shalom
> 
> -- 
> This message has been scanned for viruses and
> dangerous content by MailScanner, and is
> believed to be clean.
> 
> 

-- 
This message has been scanned for viruses and
dangerous content by MailScanner, and is
believed to be clean.