oops - mbits-mirafra/verilator GitHub Wiki

Inheritance:

                                          
//--------------------------------------------------------------------------------------------
//Inheritance:
//
//Inheritance is the mechanism which allows child class to inherit properties of parent
//class.
//--------------------------------------------------------------------------------------------

class A; // creating a class
  int a=5;   //class property
  function void disp(); // class method
    $display("1.Value of a = %0d",a);
  endfunction:disp

  endclass:A

//-------------------------------------------------------
//'extends' is the keyword which helps child class B
//to inherit the properties of base class A.
//
//-------------------------------------------------------
class B extends A; // inheritance

  int a = 6; //class B properties
  
  function void display(); //child class method
    $display("2.Value of a = %0d",a);
  endfunction:display

endclass:B

module inh_sam();
   B b1; // creating handle for class B
   initial begin
    b1 = new;    //creating an object
    b1.a = 10;  // accessing the class property
    b1.disp(); //accessing the class method of parent class 
    b1.display(); //accessing the class method of child class
    
  end
endmodule:inh_sam

Output:

Polymorphism:

                                          
class parent;
   virtual function void display();
     $display("This is parent class");
   endfunction:display
 endclass:parent

 class child1 extends parent;
   function void display();
   $display("This is child class1");
   endfunction:display
 endclass:child1

 class child2 extends parent; //child1  -same output
   function void display();
     $display("This is child class2");
     endfunction:display
 endclass:child2

 module poly_ex();
   parent p1[1:0];
   child1 c;
   child2 c2;

   initial begin
     c = new();
     c2 = new();
     p1[0] = c;
     p1[1]=c2;
     p1[0].display();
     p1[1].display();
end
 endmodule:poly_ex

Output:

Encapsulation:

local:

class parent;
   int a=10;
   local int b = 20;
  local int c = 30;

   function void display();
     $display("parent class: a= %0d, b= %0d, c= %0d", a,b,c);
   endfunction

 endclass:parent

 class child extends parent;

  function void display();
    $display("child class: a= %0d", a);
//     $display("child class: b= %0d, c= %0d", b,c); //cannot access local variable
  endfunction

 endclass:child


 module prot();

  parent p;
  child c;

  initial begin
    p = new();
    c = new();
    p.display();
//    p.c = 40;     //Cannot access local/protected member "p.d"
    c.display();
  end

endmodule:prot

Output:

Protected:

class parent;
   int a=10;
   protected int b = 20;
   protected int c = 30;

   function void display();
     $display("parent class: a= %0d, b= %0d, c= %0d", a,b,c);
   endfunction

 endclass:parent

 class child extends parent;

  function void display();
    $display("child class: a= %0d, b= %0d, c= %0d", a,b,c);
  endfunction

 endclass:child


 module prot();

  parent p;
  child c;

  initial begin
    p = new();
    c = new();
    p.display();
//    p.c = 40;     //Cannot access local/protected member "p.d"
    c.display();
  end

endmodule:prot

Output:

Abstraction:

                                          
virtual class A;
    int a,b,c;
    pure virtual function void disp();
    pure virtual task sum();
 
  endclass:A
 
  class B extends A;
 
     function void disp();    // not really necessary to add vitual here
      a =10;
      $display("1.Value of a = %0d, b = %0d, c = %0d",a,b,c);
    endfunction:disp
 
     task sum();
     c = a+b;
     $display("2.Value of a = %0d, b = %0d, c = %0d",a,b,c);
    endtask:sum
 
  endclass:B
 
  module pure_vir_fun_ex();
 
    B b1;
    initial begin
      b1 = new;
      b1.disp();
      b1.b = 35;
      b1.sum;
 
    end
 
  endmodule:pure_vir_fun_ex

Output: