OOP button with states

blinkrotate.ino

#define RED_PIN 2
#define YELLOW_PIN 3
#define BUTTON_PIN 4

struct Sketch {
  int status;
  int cur;
  int prev;
  void (*resetPins)(struct Sketch *self);
  void (*rotateState)(struct Sketch *self);
  void (*listenButtonPress)(struct Sketch *self);
};

void listenButtonPress(struct Sketch *self) {
  self->cur = digitalRead(BUTTON_PIN);

  // last reading was a button press, current is a release
  // (we want to light up on release for better UX)
  // this check is needed because all readings happen blazingly fast
  if (self->prev == LOW && self->cur == HIGH) {
    self->rotateState(self);
    delay(200); // debounce, blocking TODO: millis
  }

  self->prev = self->cur;
}

void resetPins(struct Sketch *self) {
  digitalWrite(RED_PIN, LOW);
  digitalWrite(YELLOW_PIN, LOW);
}

void rotateState(struct Sketch *self) {
  if (self->status == 0) digitalWrite(YELLOW_PIN, HIGH);
  else if (self->status == 1) {
    digitalWrite(YELLOW_PIN, LOW);
    digitalWrite(RED_PIN, HIGH);
  } else if (self->status == 2) {
    digitalWrite(YELLOW_PIN, LOW);
    digitalWrite(RED_PIN, LOW);
  }

  self->status++; // increment
  self->status = self->status % 3; // rotate (state range 0 - 2)
}

struct Sketch createSketch(void) {
  struct Sketch sk = {
    .status = 2,
    .cur = HIGH,
    .prev = HIGH,
    .resetPins = resetPins,
    .rotateState = rotateState,
    .listenButtonPress = listenButtonPress
  };
  return sk;
}

void setup() {
  pinMode(RED_PIN, OUTPUT);
  pinMode(YELLOW_PIN, OUTPUT);
  pinMode(BUTTON_PIN, INPUT_PULLUP);

  static struct Sketch sk = createSketch();
  sk.resetPins(&sk);
}

void loop() {
  static struct Sketch sk = createSketch();
  sk.listenButtonPress(&sk);
}