Re: [sv-ec] extends construct

>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.

I agree, but it's important to note here that a type_identifier cannot
denote a parameterized class.  A parameterized class can extend a
specialization of a parameterized class, but I don't think the following
sentence in 7.23 is accurate --

   "A parameterized class can extend another parameterized class."

For example, if T were a type parameter, I think it couldn't be legal to
write

   class C extends T#(32); ... endclass

-- Brad
 
-----Original Message-----
From: owner-sv-ec@eda.org [mailto:owner-sv-ec@eda.org] On Behalf Of
Gordon Vreugdenhil
Sent: Wednesday, December 20, 2006 12:37 PM
To: SV_EC List
Subject: [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