I did a little swapping of ideas with dblack on this. Now I'm
opening discussion to anyone interested.

I'm writing a little to-do manager (chiefly for my own use).

I want to allow recurring tasks. Some of these will be simple, like
"Every Monday." Others will be more complex, like "Every 2nd and 4th
Friday." Some might not even be based on weeks or months at all, but
might be like: "Every ten days, no matter what."

There'd also be an option to give advance warning (N days) on each
event.

So the question becomes: Given a date (typically "today") and a list
of recurring tasks, how do I determine which ones need to be displayed?


Cheers,
Hal