Mailman 3 re: for in dict (user expectation poll) - Python-Dev

6 Feb 2001

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On Mon, 5 Feb 2001, Greg Wilson wrote:
Based on my very-informal survey, if:
    for i in someList:
works, then many people will assume that:
    for i in someDict:
will also work, and yield values.
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Ka-Ping Yee:
...the latter is ambiguous (keys or values?)...
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Greg Wilson
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The latter is exactly as ambiguous as the former...  I think this
is a case where your (intimate) familiarity with the way Python
works now is preventing you from getting into newbie headspace...
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Ka-Ping Yee:
No, i don't think so.  It seems quite possible to argue from first
principles that if you ask to iterate over things "in" a sequence,
you clearly want the items in the sequence, not their integer indices.
Greg Wilson:
Well, arguing from first principles, Aristotle was able to demonstrate that
heavy objects fall faster than light ones :-).  I'm basing my claim on the kind
of errors students in my course make.  Even after being shown half-a-dozen
examples of Python for loops, many of them write:

    for i in someSequence:
        print someSequence[i]

in their first exercise.

Thanks,
Greg

re: for in dict (user expectation poll)

Greg Wilson

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