RE: [sv-bc] Hierarchical resolution in nested modules

The original intent was that all modules were nested modules, and the
top level module was called $root. Nested modules were also a way to
deal with the problems of having a global module namespace in
Verilog-1995.

Now that $root has disappeared as a declarative scope, and configuration
libraries in V2001 have addressed the issues of global module
namespaces, I see no reason for using nested modules.

Dave


> -----Original Message-----
> From: owner-sv-bc@server.eda.org [mailto:owner-sv-bc@server.eda.org]
On
> Behalf Of Bresticker, Shalom
> Sent: Monday, December 03, 2007 10:37 PM
> To: Steven Sharp; sv-bc@server.eda.org
> Subject: RE: [sv-bc] Hierarchical resolution in nested modules
> 
> I did not found anything about it. Nested modules are from Superlog,
> though.
> 
> I did find another issue about nested modules.
> 
> I had asked whether it was legal to instantiate a nested module before
> its definition.
> Dave Rich said yes (http://www.eda-stds.org/sv-bc/hm/4854.html).
Steven
> Sharp questioned that (http://www.eda-stds.org/sv-bc/hm/4857.html).
> 
> I found such an example in the SV 3.1a LRM (Section 18.5):
> 
> module m3(...);
> m1 i1(...); // instantiates the local m1 declared below
> m2 i4(...); // instantiates m2 - no local declaration
> module m1(...); ... endmodule // nested module declaration,
> // m1 module name is in m3's name space
> endmodule
> 
> However, this example was removed in 1800-2005. I don't know why.
> 
> Shalom
> 
> 
> 
> > >It is not even clear from the LRM that it is legal to instantiate a
> > >nested module from a scope which is lexically nested within
> > the scope
> > >where the nested module is declared. I don't object to it,
> > but the LRM
> > >does not make it clear that it is allowed.
> >
> > An intermediate interpretation of that text would be that it
> > is legal, but names cannot be bound lexically to the outer
> > module in that case.
> >
> > Whether it is illegal, legal but cannot bind lexically, or
> > legal but binds from the point of instantiation, the text
> > does not appear to support Gord's interpretation.
> >
> > Does someone know the original intent?
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