In reply to ziggy:
$cast does not create or copy objects; it tries to copy a handle from one class variable to another. Please see my course on SystemVerilog OOP, especially the second session.
In reply to dave_59:
So in the above code I have posted, Class A’s handle ‘a’ is created by ‘new’. Then I do a $cast(b,a). Why is there an error ‘type mismatch’?
But the following code works and why is that?
class A;
int a=10;
virtual function void disp();
$display("Base a=%d",a);
endfunction
endclass
class B extends A;
int a=20;
function void disp();
$display("Derived a=%d",a);
endfunction
endclass
module tb();
A a;
B b=new;
initial begin
b=a;
$cast(b,a);
b.disp(); //
$display("b.a=%d",b.a); //
a.disp(); //
$display("a.a=%d",a.a); //
end
endmodule
In reply to ziggy:
The code you just posted does not work. Did you simulate it?
b=a; // should give you a compile error
b.disp(); // should be a run time fatal because b has a null handle.
In reply to dave_59:
Sorry it was a typo
Its “a=b” and not “b=a”
In reply to ziggy:
Have you looked at my course yet?
In reply to dave_59:
Hi Dave,
Your sv-class-OOP courses are excellent !! Heavily loaded with important information. The way you described all of them seamlessly is awesome!