Optional parameters
This one may look trivial to the experts, but it took me some time to find (by pure chance) the solution to one of my problems: How to define functions or routines with optional parmeters? Overlaod is the answer!
In fact, it is extremely easy and handy. First, you write your routine/function has you would usually do. The example below blinks a led (Impressive!) and you can decide about the number of blinks, the duration of each blink and the on time ratio.
This will give you something like
void setup(){
DDRB |= (1 << PINB5);
}
void loop(){
blinkLed(500);
delay(1000);
}
// Functions
void blinkLed(int blinks, int duration, int onTimeRatio) {
int onTime = int((duration*onTimeRatio)/100);
int offTime = (duration - onTime);
for (int i=0; i < blinks; i++) {
PORTB |= (1 << PINB5); // Turn led on
delay(onTime);
PORTB &= ~(1 << PINB5); // Turn led off
delay(offTime);
}
}
But, seriously, are you so much intrested in the on time ratio while blinking a led as an activity indicator? The only thing you have to do is to append the following code to the previous lines
void blinkLed(int blinks, int duration) {
blinkLed(blinks, duration, 50);
}
Did you notice that we replaced the on time ratio by a fixed value (that we could have read from outside)?
And so on, down a minimal led blinking routine
void blinkLed(int duration) {
blinkLed(5, duration, 10);
}
void blinkLed() {
blinkLed(5, 400, 50);
}
What I found very interesting, is that you can also program this type of routine/function (if you are interested in setting the duration as the only parameter)
void blinkLed(int duration) {
blinkLed(5, duration, 10);
}
Instead of (if you are interested in setting the number of blinks as the only parameter):
void blinkLed(int blinks) {
blinkLed(blinks, 400, 50);
}
Which means (may be an expert could give more details and references) that the compiler branches to the appropriate routine/function, depending upon the number of parameters that are passed on to it, and on the type of parameter too.
void blinkLed(float onTimeRatio) {
blinkLed(5, 100, long(onTimeRatio*100));
}
void blinkLed(int onTimeRatio) {
blinkLed(5, 100, onTimeRatio);
}
void blinkLed(boolean onTimeRatio) {
if (onTimeRatio)
blinkLed(5, 100, 90);
else
blinkLed(5, 100, 10);
}
Warning: The compiler may get confused by data types (e.g. int vs long vs boolean) so that it may be necessary to cast values (e.g. (boolean)x, 0.01F, (int)x)