[sv-bc] Type parameterisation of derived classes

Subject: [sv-bc] Type parameterisation of derived classes
From: Jonathan Bromley (jonathan.bromley@doulos.com)
Date: Wed Sep 03 2003 - 03:55:37 PDT

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hi,

I sent this to sv-ec a couple of weeks ago and received no
reply. This could be for a bunch of reasons, of course.

However, I still think it's a significant issue so I'm
going to bull on ahead and be a damn nuisance by posting
it again. I've also copied it to sv-bc in case it's more
appropriate there. Thanks for your forbearance.

~~~~~~~~~~~~~~~~ repeated message begins ~~~~~~~~~~~~~~~

I have a query; I'd be grateful for clarification.

SV3.1 classes can be parameterized for type:

  class C #(parameter type T = bit);
    protected T v; // or whatever
    ...
  endclass

OK, now let's derive something from C...

  class D #(parameter type P = bit) extends C;
    ...

But I would like to be able to choose the value of C's
type parameter T, when I instantiate an object of class D.
I think I would like to be able to say

  class D #(parameter type P = bit) extends C #(.T(P));

so that the derived class's type parameter is passed
on to the base class. But the syntax doesn't seem to
allow for this, and it is not mentioned in the LRM.

I believe that this facility is important to allow the
creation of various kinds of container class. It is
available in C++ using templates. Is this a deliberate
omission from SV3.1, an oversight in the BNF, or have I
missed something?

~~~~~~~~~~~~~~~~~ repeated message ends ~~~~~~~~~~~~~~~~

-- 
Jonathan Bromley
Consultant
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