deep copy or shadow copy in your systemverilog object

as the same methodology as c/c++ or any languages. we usually used copy function to copy trx to avoid the overwrite trx when the trx had new ptr triggered. this is an sample example about what's the difference between deep copy and shadow copy, in short word. deep copy is top down copy, copy from this(current) level info to it's parents info. shadow copy is template current level copy, only for this level info.

class Based #(type T=int unsigned);
  T val;

  function new (T v=0);
    val = v; // assign new val
  endfunction : new

  virtual function void deep_copy(Based b);
    assert(b!=null);
    b.val = val; // b.val = this.val
  endfunction : deep_copy

  virtual function void shadow_copy(Based b);
    assert(b!=null);
    b.val = val; // b.val = this.val
  endfunction : shadow_copy

  virtual function bool eq(Based b);
    return b.val == val;
  endfunction : eq

endclass : Based

class A #(type T=int unsigned) extens Based;
  T val_a

  function new (T v=0);
    super.new();
    val_a = v; // assign val_a
  endfunction : new 

  virtual function void deep_copy(A a); 
    assert(a!=null);
    Based b;
    a.val_a = val_a;
    $cast(b,a);
    super.deep_copy(b);
    // or
    // a.val_a = val_a
    // a.val  = super.val
  endfunction : deep_copy

  // operator overwrite ... eq, lt, lt, ...
  virtual function bool eq(A a0);
    assert(a0!=null);
    Based b0;
    $cast(b0,a0);
    return val_a == a0.val_a & super.eq(b0);
  endfunction : eq


endclass : A


A a0 = new(1);
A a1 = new(2);

a0.val_a = 3;
a0.val = 2;

a0.deep_copy(a1);

// check a0, a1 contains are eq  a0 = a1
assert(a0.eq(a1));