Re: [sv-bc] Question on pure virtual function

Well, there generally isn't a very good reason to have the
base class defined after the derived class in the same section
of code so I would consider that to be at least bad style.

More interesting are type parameter cases (which are conceptually
similar):

     class B;
     endclass;

     module child #(type base = B);
       class derived extends base;
       endclass
     endmodule

     module top;
       virtual class base;
          pure virtual function int f();
       endclass
       child #(base) c();
     endmodule

This design should cause an error since the actual type of "base"
provided to "child" is abstract and "derived" does not override "f".
The enforcement of the class relationship rules are the same; the
time at which a particular implementation might "notice" the error
could vary but will definitely be prior to simulation time and
does not depend on the existence of a "new" call (the error is
purely a function of the type relationships).

Gord.


Surya Pratik Saha wrote:
> Hi Gordon,
> Thanks for the reply. I have another question, if the virtual base class 
> is a typedef which is declared later then how it will be handled. For e.g.
> 
> typedef class base;
> class derived extends base;
> endclass
> 
> virtual class base;
>    pure virtual function int f();
> endclass
> 
> Regards
> Surya
> 
-- 
--------------------------------------------------------------------
Gordon Vreugdenhil                                503-685-0808
Model Technology (Mentor Graphics)                gordonv@model.com


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