Alternative ButtonBoard

[bennuttall]

Currently the ButtonBoard class has an n-tuple value:

>>> bb = ButtonBoard(2, 3, 4, 5)
>>> tuple(bb.value)
(0, 0, 0, 0)

and if one button is pressed, the activated callback is fired:

>>> bb.when_pressed = lambda: print("Pressed")
>>> bb.all[0].pin.drive_low()
Pressed
>>> tuple(bb.value)
(1, 0, 0, 0)

I wondered if we could introduce a threshold, so you could specify how many active buttons were required for the event to fire, e.g:

>>> bb = ButtonBoard(2, 3, 4, 5, threshold=4)

i.e. all four buttons must be pressed for the event to fire.

@waveform80 suggested that this should be a separate class - similar to the differentiation between LEDBoard and LEDBarGraph where the new class would have a single 0-1 value rather than an n-tuple. So perhaps ButtonGroup?

This would only allow either one-button activations (with ButtonBoard) or all-button activations (with ButtonGroup) but nothing in-between (unless this can be solved with nesting mentioned in #607) - not a huge problem as I don't expect this to be too common (and can be achieved using other methods).

[lurch]

What's the imagined use-case for having a ButtonBoard that only fires it's when_pressed event when e.g. any 3 out of a possible 5 buttons are pressed? (if I'm understanding your threshold suggestion correctly)

Or are you specifically only asking for an event that fires when all buttons are pressed. Would adding an when_all_pressed event to the existing ButtonBoard class solve your requirement?

[bennuttall]

Closing this in favour of #522 - moving this discussion there