Converting a flat list to a list of tuples

Fredrik Lundh fredrik at
Wed Nov 23 13:23:21 CET 2005

Bengt Richter wrote:

> Are you thinking of something like lines from a file, where there might be
> chunky buffering? ISTM that wouldn't matter if the same next method was called.
> Here we have multiple references to the same iterator. Isn't e.g. buiding
> a plain tuple defined with evaluation one element at a time left to right?

yeah, but what says that the iterator has to be called during tuple construction?

    while 1:
        for each sequence:
            # optimize cache behaviour!
            grab up to N items from each iterator
        M = length of shortest output list
        for i in range(M):
            build tuple and append
        if M != N:


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