Perhaps I shouldn’t have mentioned “del gen”. That was meant to represent the garbage collector running and calling gen.__del__() or equivalent. Basically what I was trying to say is I think there will be two classes of generators:

1. Simple generators just implementing the plain iterator protocol, where there is nothing to clean up. In these cases a ResourceWarning is unwanted. Example: generator expressions.

2. Complex generators that have special cleanup code. Ideally the user should either exhaust the generator or call its close() method, and a ResourceWarning would be useful if neither of these happen. Example: Nick’s mygen().