Extended Parametrized class

SystemVerilog
,
1

Looking at section 8.25 Parametrized class in LRM, there is another way to override the base class parameter from extended class.

class D4 #(type P = C#(real)) extends P; // for default, T is real 
// I am assuming C#(real) overrides the base class Type.

I dont think that is happening in the below code.



typedef enum {ADD,SUB,MUL} opcode;

class A#(type T=int);
  T sub;
 
endclass


class B #(type Q = A#(real)) extends A;
  Q mux;
  
endclass



module tb;  

  B  #(real)a1;
  A base;
  
  
  initial begin
    a1 = new();
    base = new();
    a1.mux =10.23;
    base.sub = 10.45;
    $display ("Mux value in class B is %f",a1.mux);
    $display ("Sub value in class Base is %0.3f",(base.sub));
  end
  
  
  
endmodule
2

In reply to rag123:

It’s not clear what you are expecting. Your code is equivalent to

class B #(type Q = A#(real)) extends A#(int);
  Q mux; // equivalent to A#(real) mux;
 
endclass
3

In reply to dave_59:

Hi Dave,
I was expecting A Type to be have a value of real.

Example from LRM :
class D4 #(type P = C#(real)) extends P; // for default, T is real

I also found this text in one of your paper. Yin and Yan of OOP.

Parameters applied to
the extended class may propagate up to the base class.

4

In reply to rag123:

But you wrote

class B #(type Q = A#(real)) extends A;

The “extends A” is actually “extends A#()” which means “A with the default specialization”

If you wrote

class A#(type T);
  T sub;
endclass
class B #(type Q = A#(real)) extends A; // error

Then you would have gotten a compiler error because you did not provide an override for T in the second reference to A.