> `tee()` doesn't copy the iterator or its internal state but just caches > it's results, so you can iterate over them again. That makes only sense > if you expect to use the two iterators in a way they don't get much out of > sync. If your usage pattern is "consume iterator 1 fully, and then > re-iterate with iterator 2" `tee()` has no advantage over building a list > of all results of the original iterator and iterate over that twice. > `tee()` would be building this list anyway.
It's interesting and a concrete answer. Thanks a lot. > Because it's often not possible without generating a list with all > results, and the advantage of a low memory footprint is lost. > > Ciao, > Marc 'BlackJack' Rintsch Seems like "monada". But I think is possible to determine when there is a bounded external state (side-effects) or not, may be is needed some new class-protocol for it... or something else. Or another way: iterators may be re-iterable always, but if programmer need to point to the extra- (external) state, he has to raise some a special exception in __iter)) method... OK, it's only fantasies about language design :-) --pavel -- http://mail.python.org/mailman/listinfo/python-list
