I like the name idea, but I'm skeptical of the interface suggestions. The code would lose readability and my module would be a lot more complex. In Memoize, you don't lose readability because a memoize'd sub still does the same stuff regardless of weather it's cached or not. In this application the behavior is different. I can see a code maintainer going nuts because this thing only sends an email every 5 minutes, no matter what he does and he doesn't know why until he sees that defer() call at the top.

If there's demand for it, though, I'd be happy to write it with both interfaces.

Can you think of a way to make it more compact without losing readability?

Anyone else have thoughts on that?