ram <[EMAIL PROTECTED]> wrote:
> Here's a little issue I run into more than I like: I often need to
> unpack a sequence that may be too short or too long into a fixed-size
> set of items:
>
> a, b, c = seq # when seq = (1, 2, 3, 4, ...) or seq = (1, 2)
>
> What I usually do is something like this:
>
> a, b, c = (list(seq) + [None, None, None])[:3]
>
> but that just feels rather ugly to me -- is there a good Pythonic
> idiom for this?
Pythonic might be to be explicit: i.e. know in advance how long the
sequence actually is.
One drawback I see with your code is that it doesn't give you any way to
specify different defaults for the values. So here's an alternative to
consider: try passing your sequence to a function. This lets you specify
appropriate defaults, and it reads quite cleanly. Of course it also forces
you to extract the code using those variables out into a separate function,
but that may not be a bad thing.
>>> def process(a=None, b=None, c=None):
print a, b, c
>>> seq = iter('abcd')
>>> process(*itertools.islice(seq,0,3))
a b c
>>> seq = iter('ab')
>>> process(*itertools.islice(seq,0,3))
a b None
>>>
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