Added ability to bind std:function on interrupts

[straccio]

The function attachInterrupt now also accept std:function<void(void)> in order to bind object method to an interrupt.

[LMESTM]

This looks interesting, can you provide a usage example in the commit message or in the comment above new attachInterrupt function ?

considering code: please consider removing the // and simply remove the lines ?

[LMESTM]

@straccio thanks for submitting the PR :-) !
Few further questions:
Could you provide a usage example (also part of my review comments) ?
Can you confirm that this change is backward compatible - I think this is the case from reviewing the code, just would like your confirmation on this.

[straccio]

Sure!

#define USER_BUTTON_PIN D75
volatile int state = HIGH;
void bt_handler(void) {
  state = !state;
}

std::function<void(void)> bt_handler_f = bt;
void setup() {
  pinMode(LED_BUILTIN, OUTPUT);
  attachInterrupt(USER_BUTTON_PIN, bt_handler_f, FALLING);
}

void loop() {
  digitalWrite(LED_BUILTIN, state);
}

[straccio]

Is backward compatible. I currently use something like this in Arduino Due.
I have only tested on STM32F429ZI

[LMESTM]

Looks good to me (1 comment remains ..)

[straccio]

Good!
I like to add this enhancement also to wire library in order to give the ability to bind member function to wire callbacks.

If you remember others sources that use callbacks please tell me, i can do these changes also to them.

[fpistm]

Still some comment to remove.
Please, when done squash all commit in one.

You could also add your Signed-off-by: in the commit message.

Note:
Build for all variants with success (with c call and C++)

And thanks for this PR ;)

[straccio]

Thank you very much!