composition-over-inheritance.ts

interface State {
  position: number;
}

function createDog() {
  const state: State = {
    position: 0,
  };

  return {
    ...voice(),
    ...barker(),
    ...voice(),
    ...walker(state),
  };
}

function voice() {
  return {
    voice(x: string) {
      console.log(x);
    },
  };
}

function barker(this: typeof voice) {
  return {
    bark(x: string) {
      this.voice(x);
    },
  };
}

function walker(state: State) {
  return {
    walk(step: number) {
      state.position += step;
    },
  };
}