[sv-ec] extends construct

Sorry for the format of the response here; I'm still not getting
SV-EC/BC email from the reflector so it is a bit painful to respond
to any of the posts.



There are a bunch of issues in terms of exactly what
constitutes a "class identifier".  We've taken the position
that "class identifier" is any type identifier that denotes
a class.  If that were not the case then other situations
such as "T::foo();" would not work either if T were a
type parameter denoting a class.

I don't necessarily think that all "type expressions" should
be permitted.  For example, the LRM is very definite that
a type reference of the form "interface_name.type" may only
exist in a typedef.  That is a good thing due to parse
issues.  "type(va)" doesn't have the parse issues so I
don't think that there are any technical issues with allowing
it.  I guess that would also beg the question of whether
"type(va)::foo();" would be valid.  At this point, I don't
see compelling reasons to create more work for ourselves
in this area; it is easy enough to create a typedef for such
cases.

Gord.


-- 
--------------------------------------------------------------------
Gordon Vreugdenhil                                503-685-0808
Model Technology (Mentor Graphics)                gordonv@model.com

------ original email from Francoise -------
The BNF for the extends of a class declaration does not allow
type parameters or type references:

class_type ::= ps_class_identifier [ parameter_value_assignment ]

{ :: class_identifier [ parameter_value_assignment ] }



I assume that the following class declaration should be legal:

class B;

endclass

B va;

parameter type T = B;

class C extends T;

endclass



Can we also have a type reference since we can use a type reference as a
datatype for declaring

any variable?

class D extends type(va);

endclass



Francoise