Christoph Zwerschke wrote:
> Anyway, I was thinking about whether it would be possible and desirable
> to change the old behavior in future Python versions and let dict.keys()
> and dict.values() both return sets instead of lists.
You answer the question whether it would be possible (no, because of
backwards compatibility); you don't attempt to answer the question
whether it would be desirable. Why do you think that would be
a good idea?
If you want the set of keys of a dictionary d, then do set(d):
>>> d={1:2,3:4}
>>> set(d)
set([1, 3])
As Mike Meyer explains, the same is meaningless for .values():
they might not be unique. For .items(), conversion into a set
does would appear to be meaningful, but doesn't actually work:
if the values contain unhashable objects, the set of tuples
cannot be constructed (as set members must be immutable).
Regards,
Martin
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