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

>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?

No, it doesn't.  It says that 

    1)  An integer parameter can be assigned '$'.  (Perhaps there are
other sorts of data objects that can be assigned '$', perhaps not, but
this statement is silent on that issue.)

    2)  An integer parameter that has been assigned '$' can only be
legally referred to in contexts where '$' would anyway be legal.

-- Brad

-----Original Message-----
From: owner-sv-ac@eda.org [mailto:owner-sv-ac@eda.org] On Behalf Of John
Havlicek
Sent: Sunday, August 19, 2007 3:10 PM
To: shalom.bresticker@intel.com
Cc: john.havlicek@freescale.com; sv-ac@eda-stds.org
Subject: 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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> 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>
> > > X-OriginalArrivalTime: 16 Aug 2007 06:15:59.0713 (UTC)=20  
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> > >more=20  information
> > > X-eda.org-MailScanner-From: owner-sv-ac@server.eda.org =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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