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

Hi Shalom:

This is interesting.  We have thought for a long time
that $ can be passed as actual argument to sequence and 
property instances.  I think tools support this too.

Does the statement in 6.20.2.1 actually imply that $
can be assigned only to parameters and then only to 
ones of integer types?  That is not the way I read it.

I also do not like the turn of phrase 

  "An actual argument can replace any of the following:"


Best regards,

J.H.

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> Thread-Topic: [sv-ac] call to vote on 1549
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> From: "Bresticker, Shalom" <shalom.bresticker@intel.com>
> Cc: <sv-ac@eda-stds.org>
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> 
> John,
> 
> I looked at this a little.
> 
> Mantis 1350 discusses ambiguities with respect to the use of $, but the
> basic restrictions are stated at the beginning of 6.20.2.1:
> 
> "The value $ can be assigned to parameters of integer types. A parameter
> to which $ is assigned shall only be used wherever $ can be specified as
> a literal constant."
> 
> Assigning $ to a variable does not fit those criteria.
> Nor does passing $ as an argument.
> You mentioned passing $ "as actual argument expression to a typed formal
> argument."
> I do not see that it could be passed even to an untyped formal argument.
> 
> I doubt even that what is written in 16.7 meets those criteria:
> 
> "An actual argument can replace any of the following:
>  ...
>  - Upper delay range or repetition range if the actual argument is $"
> 
> Regards,
> Shalom
> 
> 
> > -----Original Message-----
> > From: John Havlicek [mailto:john.havlicek@freescale.com]=20
> > Sent: Friday, August 17, 2007 2:32 PM
> > To: Bresticker, Shalom
> > Cc: Bustan, Doron; Yaniv.Fais@freescale.com; sv-ac@eda-stds.org
> > Subject: Re: [sv-ac] call to vote on 1549
> >=20
> > Hi Shalom:
> >=20
> > Lisa and I had a discussion yesterday about the example in=20
> > the 1549 proposal.
> >=20
> > I do not think the LRM as it stands now allows $ to be=20
> > assigned to a variable or passed as actual argument=20
> > expression to a typed formal argument.  Do you know otherwise?
> >=20
> > The main conceptual issue that I see with allowing $ to be=20
> > assigned to a variable or passed as actual argument=20
> > expression to a typed formal argument is defining what value=20
> > it has in the space of possible values for the associated data type.
> >=20
> > It doesn't seem quite right to me to say that if $ is=20
> > assigned to a shortint, for example, then the value is the=20
> > largest one that can be represented in an shortint.  On the=20
> > other hand, maybe this is a useful and sensible definition. =20
> > With definitions of this kind, the meaning of $ is dependent=20
> > on the data type into which it is assigned or to which it is=20
> > bound, but there is already precedent for that in the various=20
> > coercion rules.
> >=20
> > I recommended that we avoid this problem altogether for now=20
> > and not allow $ to be assigned to a variable or passed as=20
> > actual argument expression to a typed formal argument.  I=20
> > recommended that Lisa change the example to pass $ to a=20
> > context formal argument.
> >=20
> > J.H.
> >=20
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> > > From: "Bresticker, Shalom" <shalom.bresticker@intel.com>
> > > Cc: <sv-ac@eda-stds.org>
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> > >=20
> > > The LRM states in other places restrictions on the use of $.=20
> > > The question is whether the example fulfills those conditions.
> > >=20
> > > The following quoted wording is a little unclear:=20
> > >=20
> > > > An actual argument can replace any of the following:
> > > > - Identifier
> > > > - Expression
> > > > - Event control expression
> > > > - Upper delay range or repetition range if the actual=20
> > argument is $
> > >=20
> > > "can replace" seems a little problematic here.
> > > An actual argument cannot really replace an expression. E.g., it=20
> > > cannot replace a+b. It can replace a formal argument which=20
> > is used as=20
> > > an expression, which is a little different.
> > >=20
> > > And does this list cover all the possibilities, or is it=20
> > just intended=20
> > > to be examples?
> > >=20
> > > And does the last item mean:
> > > 1. If the actual argument is $, it can be used only in this=20
> > way? If it=20
> > > is not $, can it be used in this way?
> > > 2. It can be used in this way only if it is $? If it is $,=20
> > can it be=20
> > > used in another way?

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