1. 使用new操作符复制一个对象
1 class Header;
2 int id;
3 function new (int id);
4 this.id = id;
5 endfunction
6
7 function showId();
8 $display ("id=0x%0d", id);
9 endfunction
10 endclass
11
12 class Packet;
13 int addr;
14 int data;
15 Header hdr;
16
17 function new (int addr, int data, int id);
18 hdr = new (id);
19 this.addr = addr;
20 this.data = data;
21 endfunction
22
23 function display (string name);
24 $display ("[%s] addr=0x%0h data=0x%0h id=%0d", name, addr, data, hdr.id);
25 endfunction
26 endclass
27
28 module tb;
29 Packet p1, p2;
30 initial begin
31 // Create a new pkt object called p1
32 p1 = new (32'hface_cafe, 32'h1234_5678, 26);
33 p1.display ("p1");
34
35 // Shallow copy p1 into p2; p2 is a new object with contents in p1
36 p2 = new p1;
37 p2.display ("p2");
38
39 // Now let's change the addr and id in p1
40 p1.addr = 32'habcd_ef12;
41 p1.data = 32'h5a5a_5a5a;
42 p1.hdr.id = 17;
43 p1.display ("p1");
44
45 // Print p2 and see that hdr.id points to the hdr in p1, while
46 // addr and data remain unchanged.
47 p2.display ("p2");
48 end
49 endmodule
这是一种简易复制（shallow copy），原对象的值被盲目copy到对象中，如果类A1中包含一个指向另一个子类B的句柄，那么复制类A2中只是复制了子类B的句柄，A1和A2中的B对象指向的是同一个对象。
2. 定义copy函数，实现深拷贝
1 class Header;
2 int id;
3 function new (int id);
4 this.id = id;
5 endfunction
6
7 function showId();
8 $display ("id=0x%0d", id);
9 endfunction
10 endclass
11
12 class Packet;
13 int addr;
14 int data;
15 Header hdr;
16
17 function new (int addr, int data, int id);
18 hdr = new (id);
19 this.addr = addr;
20 this.data = data;
21 endfunction
22
23 function copy (Packet p);
24 this.addr = p.addr;
25 this.data = p.data;
26 this.hdr.id = p.hdr.id;
27 endfunction
28
29 function display (string name);
30 $display ("[%s] addr=0x%0h data=0x%0h id=%0d", name, addr, data, hdr.id);
31 endfunction
32 endclass
33
34 module tb;
35 Packet p1, p2;
36 initial begin
37 p1 = new (32'hface_cafe, 32'h1234_5678, 32'h1a);
38 p1.display ("p1");
39
40 p2 = new (1,2,3); // give some values
41 p2.copy (p1);
42 p2.display ("p2");
43
44 // Now let's change the addr and id in p1
45 p1.addr = 32'habcd_ef12;
46 p1.data = 32'h5a5a_5a5a;
47 p1.hdr.id = 32'h11;
48 p1.display ("p1");
49
50 // Now let's print p2 - you'll see the changes made to hdr id
51 // but not addr
52 p2.display ("p2");
53 end
54 endmodule
来源：https://www.cnblogs.com/littleMa/p/12345263.html