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SystemVerilog OOP Mastery · All levels

Classes and Objects: Code Examples

Code Examples for Classes and Objects.

Code examples

Declaring a handle versus constructing an object

systemverilog
class packet;
  rand bit [31:0] addr;
  rand bit [31:0] data;
endclass

module demo;
  initial begin
    packet p;                // handle only, currently null
    if (p == null) $display("p is null before new");

    p = new();               // object allocated now
    assert(p.randomize());
    $display("addr=%0h data=%0h", p.addr, p.data);
  end
endmodule

Shows the exact transition from null handle to allocated object, then randomization on a valid object.

Independent objects from same class type

systemverilog
class txn;
  rand bit [7:0] id;
endclass

module demo2;
  initial begin
    txn t1 = new();
    txn t2 = new();
    t1.id = 8'hA5;
    t2.id = 8'h3C;
    $display("t1.id=%0h t2.id=%0h", t1.id, t2.id);
  end
endmodule

Demonstrates that two handles constructed with separate new() calls point to distinct objects.

Centralized object creation helper

systemverilog
class packet;
  rand int unsigned length;
  function void post_randomize();
    if (length == 0) length = 1;
  endfunction
endclass

function packet make_packet();
  packet p = new();
  assert(p.randomize() with { length inside {[1:64]}; });
  return p;
endfunction

Encapsulates allocation plus initialization so callers never touch uninitialized handles.

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