In reply to Debasmita:
Consider this code snippet to understand,
Inheritance -
Class A;
//Properties and Methods
endclass
Class B extends A;
//Properties and Methods
endclass
By means of inheritance you can reuse previously written classes to extend functionality of your blocks. Best example is UVM base class library. By extending our class from uvm classes we can make use of inherited properties and methods(tlm ports, phases etc.)
Polymorphism -
Class A;
//Properties and Methods
virtual function void display();
$display();
endfunction
endclass
Class B extends A;
//Properties and Methods
function void display();
$display();
endfunction
endclass
A a_h;
B b_h;
initial
begin
b_h = new();
a_h = b_h;
a_h.display(); //Calls extended class B method display by means of Polymorphism
end
- When inheritance is in picture, one can hide parent class properties/methods by declaring same set in extended class as well.
- So, when creating extended class objects and using it in existing testbench (with same old parent class handles) to access these new extended class methods polymorphism is required.