On Sun, 2009-06-14 at 23:01 +1000, Steven D'Aprano wrote:
> Write a helper function:
>
> def getitems(L, *indexes):
> if len(indexes) == 1:
> indexes = indexes[0]
> return [L[i] for i in indexes]
>
Whoops! Your example is broken:
>>> cars = ['Ford', 'Toyota', 'Edsel']
>>> getitems(cars, 1)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "<stdin>", line 4, in getitems
TypeError: 'int' object is not iterable
>>>
I think you meant to apply that [0] to the created list instead.
Something like:
def getitems(L, *indexes):
new_list = [L[i] for i in indexes]
if len(indexes) == 1:
new_list = new_list[0]
return new_list
But I'm not sure that would be the best idea anyway. Just let getitems
always return a list. That way the caller doesn't have to test the
length to figure out what to do with it. If you know you want a single
item, you can use regular old .__getitem__ (or .get) methods, or direct
indexing.
Then getitems can just be:
def getitems(L, *indexes):
return [L[i] for i in indexes]
>
> But I think this is an obvious enough extension to the __getitem__ protocol
> that I for one would vote +1 on it being added to Python sequence objects
> (lists, tuples, strings).
>
I'd be +0. It won't change my life, but it seems like a decent idea.
>
> --
> Steven
>
Cheers,
Cliff
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