RE: [sv-ec] class related questions

Thanks Dave,
 
I agree with 1 but disagree that we should allow 2).
Seems like a bad idea to consider C::q as a constant expression.
Class declarations can be declared much later in the source code since
we allow forward type declarations.
We could end up with circular dependencies where p in the module depends
on a parameter declared in 
a class specialization and the class depends on the module parameter.
Sounds safer to disallow this, no?
 
Also can we use C::q (class scope parameter) in a range?
Francoise
       '


________________________________

	From: Rich, Dave [mailto:Dave_Rich@mentor.com] 
	Sent: Wednesday, July 09, 2008 5:21 PM
	To: Francoise Martinolle; sv-ec@eda.org
	Subject: RE: [sv-ec] class related questions
	
	
	
________________________________


	From: owner-sv-ec@server.eda.org
[mailto:owner-sv-ec@server.eda.org] On Behalf Of Francoise Martinolle
	Sent: Wednesday, July 09, 2008 1:29 PM
	To: sv-ec@server.eda.org
	Subject: [sv-ec] class related questions

	 

	Question 1:

	Can you use the "dot" to refer to a type declared inside a
class?

	module top;

	class C;

	  typedef bit T[4];

	endclass

	C c = new;

	   bit b;

	   initial

	      b = c.T'{0, 1, 0, 1};

	endmodule

	 

	The bnf for assignment pattern type does not allow the above,
neither

	does it allow C::T'{0, 1, 0, 1}

	 

	I also remember that we decided that hierarchical identifiers to
types are not legal, but does c.T qualifies

	as a hierarchical identifier? or is it just what we called a
dotted name?

	[DR] You can not use a dotted name as a type. The only exception
is with an interface port. And had introduced the scope operator '::' at
the time, we should have used that instead of allowing '.'.

	 

	I think C::T should be allowed as we have used it resolve Mantis
1857. It might be an oversight in the BNF.

	 

	 

	Question 2:

	 

	Can a parameter initial expression be a class scoped identifier?

	The LRM currently only allows package references. I assume this
is not legal:

	 

	module top;

	class C #(parameter q = 0, parameter type T = byte);

	endclass

	 

	parameter p = C::q;

	parameter type R = C::T;

	 

	endmodule

	[DR] Again, I think there is LRM text to support this usage in
terms of parameters that are nested in classes, but no BNF. For example
T::p refers to the parameter up in the class hierarchy.

	 

	class C #(parameter p = 0) extends T;

	parameter q = T::p;

	endclass

	 

	Another example, T::p refers to a parameter within the class

	class C #(parameter type T = int);

	parameter q = T::p;

	endclass

	 

	.

	 


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