class PushButton {
private:
  int pin;
  bool state;
  void (*action)();

public:
  PushButton(int pin, void (*action)()) {
    this->pin = pin;
    this->action = action;
    pinMode(pin, INPUT);
    state = digitalRead(pin);
  }

  void update() {
    bool newState = digitalRead(pin);
    if (newState != state) {
      state = newState;
      if (state == HIGH) {
        action();
      }
    }
  }
};

void say_hello() {
  Serial.println("Hello!");
}

PushButton button(2, say_hello);

void setup() {
  Serial.begin(9600);
}

void loop() {
  button.update();
  delay(10); // Jeda untuk stabilitas pembacaan tombol
}