calloverhead of methods of structs and classes

structs_vs_classes.d

import std.datetime;
import std.stdio : writeln;

struct HStruct {
  size_t c;

  void add() {
    c = c % 3 +1;
  }
  size_t get() {
    return c;
  }
}

final class HClass {
  size_t c;
  final void add() {
    c = c % 3 +1;
  }
  final size_t get() {
    return c;
  }
}

int main(string[] args) {
  auto sw = StopWatch(AutoStart.no);
  {
    sw.start();
    HStruct h;
    for (size_t i = 0; i<1_000_000; ++i) {
      for (size_t j = 0; j<1_000; ++j) {
        h.add();
      }
    }
    sw.stop();
    writeln("time with struct: ", sw.peek().msecs, " for ", h.get());
  }
  {
    auto h = new HClass();
    sw.start();
    for (size_t i = 0; i<1_000_000; ++i) {
      for (size_t j = 0; j<1_000; ++j) {
        h.add();
      }
    }
    sw.stop();
    writeln("time with class: ", sw.peek().msecs, " for ", h.get());
  }
  return 0;
}