Re: [sv-bc] Mantis 1809

Shalom,

I don't think this is legal (or really should be).  The LRM
has:

    package_scope ::=
         package_identifier ::
       | $unit ::

and "import" requires a package_identifier, it doesn't go
through the "package_scope" production.  So the grammar
currently does not allow import from $unit.

I think that is appropriate conceptually and in practice.

$unit is very special -- there are a bunch of special rules
regarding function and non-function name resolution for $unit
that don't apply to normal packages.  The assumption of
"import" is that a package is complete and that one can
import *any* direct identifier from the package.  But $unit may
not yet be complete so if one wanted import from $unit, we'd
have to define another set of special rules that would deal
with forward visibility issues; essentially that an import
could only be equivalent to a legal direct reference.

The only reason to have import of $unit in any case would be
to have a shortcut for $unit::<ident> in nested scopes where
there are a large number of intervening "hiding" declarations
that you wanted to skip over in the lexical search.  Since this
*is* a lexical search, I would suggest that such code is very badly
structured and that I'm certainly not willing to further
convolute the standard to make such a style easier to write.

Gord.


Bresticker, Shalom wrote:
> Is it allowed to do an import (specific or wildcard) from $unit?
>  
> E.g.,
> import $unit::b ;
> or
> import $unit::* ?
>  
> What about from std?
>  
> Thanks,
> Shalom
> 
>     ------------------------------------------------------------------------
>     *From:* owner-sv-bc@server.eda.org
>     [mailto:owner-sv-bc@server.eda.org] *On Behalf Of *Brad Pierce
>     *Sent:* Monday, July 21, 2008 12:06 PM
>     *To:* sv-bc@server.eda.org
>     *Subject:* RE: [sv-bc] Mantis 1809
> 
>     Proposal is attached for easier review.
> 
>      
> 
>     n  Brad
> 
>      
> 
>     *From:* owner-sv-bc@eda.org [mailto:owner-sv-bc@eda.org] *On Behalf
>     Of *Rich, Dave
>     *Sent:* Monday, July 21, 2008 4:56 PM
>     *To:* sv-bc@eda.org
>     *Subject:* [sv-bc] Mantis 1809
> 
>      
> 
>     New proposal uploaded and should be reviewed. It’s very late.
> 
>      
> 
>     David Rich
>     Verification Technologist
>     Design Verification & Test Division
>     Mentor Graphics Corporation
>     dave_rich@mentor.com
>     Office:   408 487-7206
>     Cell:     510 589-2625
> 
>      
> 
> 
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Gordon Vreugdenhil                                503-685-0808
Model Technology (Mentor Graphics)                gordonv@model.com


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