On Wed, 30 Sep 2015 at 09:38 Neil Girdhar <mistersheik@gmail.com> wrote:

In fairness, one is a superset of the other.  You always get an Iterable.  You sometimes get a Sequence.  It's a bit like multiplication? with integers you get integers, with floats, you get floats.

No, it's not like multiplication. =) I hate saying this since I think it's tossed around too much, but int/float substitution doesn't lead to a Liskov substitution violation like substituting out a sequence for an iterator (which is what will happen if the type of the argument to `enumerate` changes). And since you can just call `list` or `tuple` on enumerate and get exactly what you're after without potential bugs cropping up if you don't realize from afar you're affecting an assumption someone made, I'm -1000 on this idea.

-Brett

 

On Wed, Sep 30, 2015 at 12:35 PM Brett Cannon <brett@python.org> wrote:

On Wed, 30 Sep 2015 at 08:28 Neil Girdhar <mistersheik@gmail.com> wrote:

What are the pros and cons of making enumerate a sequence if its argument is a sequence?

I found myself writing:

                for vertex, height in zip(

                        self.cache.height_to_vertex[height_slice],

                        range(height_slice.start, height_slice.stop)):

I would have preferred:

                for height, vertex in enumerate(

                        self.cache.height_to_vertex)[height_slice]:

Because you now suddenly have different types and semantics of what enumerate() returns based on its argument which is easy to mess up if self.cache.height_to_vertex became an iterator object itself instead of a sequence object. It's also not hard to simply do `tuple(enumerate(...))` to get the exact semantics you want: TOOWTDI.

IOW all I see are cons. =)