Tip: when or how to cancel a task

[philj404]

About canceling a task

(This tip was extracted from #34 ; Since it is a recurring question it probably deserves its own subject line.)

timer.tick() checks each pending task one at a time, sees if it is ready, and if so executes it.

So if your repetitive taskA wants to cancel itself, all it needs to do is return false. (It should not call timer.cancel().)

Non-repetitive tasks (the timer.in(...) and timer.at(...) tasks) don't need to cancel themselves because they only run once anyway. Since they are only going to run once it does not matter what they return.

If a different task taskB is running and discovers it needs to cancel obsolete taskA, then taskA is not running. taskB can cancel pending taskA using timer.cancel(...). Since taskA was not running and it got cancelled, it doesn't matter what it would have returned.

[philj404]

(experiment: trying to mark this Q&A as "answered")