LED flasher for Arduino without delays

flasher.h

class Flasher
{
	int ledPin;      // the number of the LED pin
	long OnTime;     // milliseconds of on-time
	long OffTime;    // milliseconds of off-time

	// These maintain the current state
	int ledState;             		// ledState used to set the LED
	unsigned long previousMillis;  	// will store last time LED was updated

    bool flashing;
	unsigned long flashingStarted;
    unsigned long flashingTime;

  public:

  Flasher(int pin, long on, long off)
  {
	ledPin = pin;
	pinMode(ledPin, OUTPUT);     
	  
	OnTime = on;
	OffTime = off;
	
	ledState = LOW; 
	previousMillis = 0;
  }

    void flash(int howlong = 1000) {
        flashing = true;
        flashingStarted = millis();
        flashingTime = howlong;
    }

    void stop() {
        flashing = false;
    }

  void update()
  {
    // check to see if it's time to change the state of the LED
    unsigned long currentMillis = millis();

    if(flashing && (currentMillis - flashingStarted) >= flashingTime ) {
        stop();
    }
    
    if(flashing) {
        if((ledState == HIGH) && (currentMillis - previousMillis >= OnTime))
        {
            ledState = LOW;  // Turn it off
        previousMillis = currentMillis;  // Remember the time
        digitalWrite(ledPin, ledState);  // Update the actual LED
        }
        else if ((ledState == LOW) && (currentMillis - previousMillis >= OffTime))
        {
        ledState = HIGH;  // turn it on
        previousMillis = currentMillis;   // Remember the time
        digitalWrite(ledPin, ledState);	  // Update the actual LED
        }
    }

  } // update ()

}; // class