Brendan Scott, author of 'Python for Kids for Dummies' is revising his
book to produce a Python 3 version. Great so far.
Unfortunately, he thinks that Python 3 turned range() into a (generator)
function that produces a generator, one that can be indexed and sliced.
I left a comment on his blog explaining that range() still produces
arithmetic sequence objects. The difference is that in Py 3, the
compact representation is not expanded to a verbose (and redundant)
Python list until requested. It is *not* like map and filter, which
*were* changed to return iterators.
For whatever reason, my comment had no effect and today on
https://python4kids.brendanscott.com/2016/08/21/python-for-kids-python-3-project-7/
he still says, near the top
>>> # range(10) is no longer a list. Rather, it's a generator
>>> # so the [:] operator slices the generator. You can use list()
>>> # to see what list the generator corresponds to.
I left a second comment, again with interactive code examples, but I
fear the result (nothing) will be the same. We cannot stop people from
publishing such misleading dis-information, but we can discourage it,
and I think we should, especially if we can before paper copies are
printed. Beginners have enough problem with iterables versus iterators
without a major beginner book confusing the two. I imagine this leading
to tutor-list and Stackoverflow questions like "Why doesn't slicing my
generator work? It did for range?"
So, if you agree with me, please either write Brendan personally if you
know him, or just leave your own comment on the blog.
--
Terry Jan Reedy
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