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SystemVerilog OOP Mastery · All levels

Handles, new(), and Construction Patterns: Code Examples

Code Examples for Handles, new(), and Construction Patterns.

Code examples

Aliasing by handle assignment

systemverilog
class packet;
  string name;
  int unsigned size;
  function new(string name = "pkt");
    this.name = name;
    this.size = 0;
  endfunction
endclass

module alias_demo;
  initial begin
    packet p1 = new("tx0");
    packet p2;
    p2 = p1;                  // handle copy, same object
    p2.size = 64;
    $display("p1.size=%0d p2.size=%0d", p1.size, p2.size);
  end
endmodule

Uses constructor parameters and shows that assigning one handle to another aliases a single object.

Deep copy with clone pattern

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

  function packet clone();
    packet c = new();
    c.addr = this.addr;
    c.data = this.data;
    return c;
  endfunction
endclass

module clone_demo;
  initial begin
    packet src = new();
    packet dst;
    assert(src.randomize());
    dst = src.clone();
    dst.addr = 'hDEADBEEF;
    $display("src.addr=%0h dst.addr=%0h", src.addr, dst.addr);
  end
endmodule

Shows a safe snapshot copy where later edits to dst do not mutate src.

Null-safe lazy construction helper

systemverilog
class fifo_cfg;
  int unsigned depth;
  function new(int unsigned depth = 16);
    this.depth = depth;
  endfunction
endclass

class env;
  fifo_cfg cfg;

  function void ensure_cfg();
    if (cfg == null) cfg = new(32);
  endfunction

  function int unsigned get_depth();
    ensure_cfg();
    return cfg.depth;
  endfunction
endclass

Demonstrates one common pattern: guard all dereferences by ensuring construction in one place.

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