RE: [sv-ec] RE: [sv-bc] Final blocks in packages

Dave is correct. The LRM allows any type data of initialization in
packages. It does not distinguish class constructors from any other type
of function. The LRM does disallow processes within packages, but the
language is unclear since it does not specify what "contain a process"
means. Does it mean a task containing statements that can fork off a
process, or does it mean implicitly initializing a process --- as, for
example, described by the following sentence regarding continuous
assignments. Prohibiting any sort of process from within a package may
be too restrictive and perhaps arbitrary. This language is in need of
clarification.

As for Doug's original question, initializing class variables in
packages is definitely useful, though most of the time the objects are
not created --- instead, they are initialized to null. There are some
uses for starting processes from within a class; typically some sort of
monitor. But that type of implicit process creation is rare because
typically tests exhibit other order dependencies --- e.g., the
environment and configuration must be initialized first. Usually,
transactors are started under explicit user control. Therefore, I think
that a restriction to disallow implicit process creation with packages
is not a bad thing at this time. As Doug wrote, if we discover a use
model that requires such a feature, we can consider relaxing this
restriction.

	Arturo

-----Original Message-----
From: owner-sv-ec@eda.org [mailto:owner-sv-ec@eda.org] On Behalf Of
Rich, Dave
Sent: Monday, May 15, 2006 1:25 PM
To: Brad Pierce; sv-ec@eda.org
Subject: [sv-ec] RE: [sv-bc] Final blocks in packages

Responding to just sv-ec to keep the traffic down,

I talked with Doug earlier today and we came to the conclusion that
calling a constructor is no different than initializing any kind of
variable with a function call, all of which is currently legal.

What's currently illegal in a package is anything within the language
that creates a thread. The PLI, of course, can do lots of things that
can't be done through the source text.

Dave




> -----Original Message-----
> From: owner-sv-bc@server.eda.org [mailto:owner-sv-bc@server.eda.org]
On
> Behalf Of Brad Pierce
> Sent: Monday, May 15, 2006 12:40 PM
> To: sv-ec@server.eda.org
> Cc: sv-bc@server.eda.org
> Subject: Re: [sv-bc] Final blocks in packages
> 
> Doug,
> 
> Is it legal today to initialize class variables in a package scope?
> 
> -- Brad
> 
> -----Original Message-----
> From: Warmke, Doug [mailto:doug_warmke@mentor.com]
> Sent: Monday, May 15, 2006 7:57 AM
> To: Vreugdenhil, Gordon; Brad Pierce
> Cc: sv-bc@eda.org
> Subject: RE: [sv-bc] Final blocks in packages
> 
> Hi all,
> 
> One question that has come to my mind during this debate:
> 
>    How useful do folks feel it would be to allow the initialization
>    of class variables declared in package scope?
> 
> I can personally envision some uses of that construct.
> But I'm wondering if other people are already using it
> or are planning on using it?  If it turns out to be a very
> useful or high demand feature, it will be worth investing
> some time into exploring "threads in packages" more deeply.
> 
> If folks don't care about it too much, then we should lower the
> priority on the discussion.
> 
> One thing to watch out for, though, is letting the barn door open
> too early.  If some implementations do allow the use of "new" in
> package VDA's, then we will likely have to deal with all this at
> some point in the future, and it could be thorny.
> 
> Regards,
> Doug
> 
> 
> 
> > -----Original Message-----
> > From: owner-sv-bc@server.eda.org
> > [mailto:owner-sv-bc@server.eda.org] On Behalf Of Vreugdenhil, Gordon
> > Sent: Wednesday, May 10, 2006 10:15 AM
> > To: Brad Pierce
> > Cc: sv-bc@server.eda.org
> > Subject: Re: [sv-bc] Final blocks in packages
> >
> >
> >
> > Brad Pierce wrote:
> >
> > > Do variable declaration assignments in a package occur only if the
> > > variable is imported?
> >
> >
> > If the "variable" is imported?  No - that would be far to fine a
> > granularity to handle.  Package dependencies are determined
> > at the "package" level -- as far as I am concerned, if a package
> > is used in the design (referenced in an import or included via
> > some other vendor mechanism) then all of its initializations
> > occur.  A reference to the package is sufficient -- no actual
> > import needs to occur.  Obviously, as with any declaration, if the
> > effect of the initialization is not observable in the design,
> > an implementation can optimize such initialization away.
> >
> >
> > Gord.
> >
> >
> > >
> > >
> > >
> > > -- Brad
> > >
> > >
> > >
> > >
> > --------------------------------------------------------------
> > ----------
> > >
> > > From: Rich, Dave [mailto:Dave_Rich@mentor.com]
> > > Sent: Tuesday, May 09, 2006 6:40 PM
> > > To: Brad Pierce; sv-bc@eda.org
> > > Subject: RE: [sv-bc] Final blocks in packages
> > >
> > >
> > >
> > > Does someone have to import the package or refer to an item
> > in a packed
> > > for the final block to execute? I would think so; otherwise
> > it would be
> > > difficult to manage the exclusion of packages that you did
> > not want to
> > > execute.
> > >
> > >
> > >
> > > Independently of whether final blocks in packages are a
> > "good idea", I
> > > don't think it is a priority worth discussing right now.
> > >
> > >
> > >
> > > Dave
> > >
> > >
> > >
> > >
> > >
> > >
> > --------------------------------------------------------------
> > ----------
> > >
> > > From: owner-sv-bc@server.eda.org
> > [mailto:owner-sv-bc@server.eda.org] On
> > > Behalf Of Brad Pierce
> > > Sent: Tuesday, May 09, 2006 6:29 PM
> > > To: sv-bc@server.eda.org
> > > Subject: Re: [sv-bc] Final blocks in packages
> > >
> > >
> > >
> > > Following up on http://www.eda.org/sv-bc/hm/4421.html ,
> > does any extra
> > > text need to be added to explain how final blocks in
> > packages execute?
> > >
> > >
> > >
> > > In my opinion, no.  I think it would be sufficient for a
> > proposal only
> > > to add final blocks to the 19.2 list of items that can be
> > shared via
> > > packages and in the BNF to move "final_construct" out of
> > its current
> > > locations and into "package_or_generate_item_declaration".
> > >
> > >
> > >
> > > Independently of whether final blocks in packages is a
> > "good idea", does
> > > the above seem like a sufficient way to modify the LRM if it were?
> > >
> > >
> > >
> > > -- Brad
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> >
> > --
> > --------------------------------------------------------------------
> > Gordon Vreugdenhil                                503-685-0808
> > Model Technology (Mentor Graphics)                gordonv@model.com
> >