Getters versus fields

gistfile1.dart

// On my laptop, I get:
// getter run 1: 73ms
// getter run 3: 64ms
// getter run 11: 63ms
// getter run 12: 14ms
// getter run 30: 13ms
// field run 1: 68ms
// field run 7: 64ms
// field run 9: 63ms

const NUM_TRIALS = 100;
const NUM_ITERATIONS = 1000000;

void main(List<String> args) {
  run("field", () {
    var objs = [];
    for (var i = 0; i < NUM_ITERATIONS; i++) {
      objs.add(new Field());
    }

    var sum = 0;
    for (var obj in objs) {
      sum += obj.a.length + obj.b.length + obj.c.length;
    }

    if (sum != NUM_ITERATIONS * 3) throw "!";
  });

  run("getter", () {
    var objs = [];
    for (var i = 0; i < NUM_ITERATIONS; i++) {
      objs.add(new Getter());
    }

    var sum = 0;
    for (var obj in objs) {
      sum += obj.a.length + obj.b.length + obj.c.length;
    }

    if (sum != NUM_ITERATIONS * 3) throw "!";
  });
}

abstract class Base {
  int get a;
  int get b;
  int get c;
}

class Field implements Base {
  final a = "a";
  final b = "b";
  final c = "c";
}

class Getter implements Base {
  get a => "a";
  get b => "b";
  get c => "c";
}

void run(String label, callback()) {
  var best = 99999999.0;

  // Run the benchmark several times. This ensures the VM is warmed up and lets
  // us see how much variance there is.
  for (var i = 0; i <= NUM_TRIALS; i++) {
    var start = new DateTime.now();

    callback();

    var elapsed = new DateTime.now().difference(start).inMilliseconds;

    // Keep track of the best run so far.
    if (elapsed >= best) continue;
    best = elapsed;

    // Don't print the first run. It's always terrible since the VM hasn't
    // warmed up yet.
    if (i == 0) continue;
    print("$label run $i: ${elapsed}ms");
  }
}