The more I read the discussion, the more zip_strict() feels like an anti-pattern to me.
I've used zip_longest occasionally, but never really hit a need for zip_strict() ... which obviously I could have written in a few lines if I wanted it. Since I never know how many elements an iterator has let—including perhaps infinity—any such function has to be leap-before-you-look. But the effect is that is that I wind up consuming more than I want of some iterators. Let's sayI have this code: >>> it1 = iter([1,2,3]) >>> it2 = iter([4,5]) >>> it3 = iter([6,7,8, 9]) >>> list(zip(it1, it2, it3)) [(1, 4, 6), (2, 5, 7)] >>> next(it3) 8 That seems fine. If I had used zip_longest() I could get some extra tuples, and indeed I'd have to check whether there were sentinel values inside of them. Depending on what I was doing, the non-sentinels might still be useful for my processing though. But this hypothetical zip_strict() (or I guess actual very recently in itertools, but I haven't checked the semantics) would raise an exception of some kind instead. It's not easier to check for an exception than it is for a sentinel, so that really don't get us anything at all in terms of saving code or clarity. If anything, the check-for-sentinel feels slightly cleaner to me. But worse is that most versions being discussed here seem to consume the 8 from it3 before raising the exception (perhaps sticking it in the exception object). I guess if it's stashed in the exception object it's not entirely lost. Still, in my code it3 remains a perfectly good iterator that I can keep around to pull more values from. Under the zip_strict approach, I have to dig a value out of the exception object before proceeding on normal iteration of it3 later in my code. That just feels awkward to me. Not un-doable, but certainly not easier. -- Keeping medicines from the bloodstreams of the sick; food from the bellies of the hungry; books from the hands of the uneducated; technology from the underdeveloped; and putting advocates of freedom in prisons. Intellectual property is to the 21st century what the slave trade was to the 16th.
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