Home Original page

[Python-ideas] Generators are iterators

Guido van Rossum guido at python.org
Wed Dec 10 21:46:11 CET 2014 
I have replaced the confusing paragraph with this:

"""
The proposal does not change the relationship between generators and
iterators: a generator object is still an iterator, and not all
iterators are generators.  Generators have additional methods that
iterators don't have, like ``send`` and ``throw``.  All this is
unchanged.  Nothing changes for generator users -- only authors of
generator functions may have to learn something new.
"""

Let us know if there is still confusion about what the PEP means.

--Guido

On Wed, Dec 10, 2014 at 10:13 AM, Guido van Rossum <guido at python.org> wrote:

> Everyone (including Chris), hold your horses. I will come up with better
> words for the PEP. I apologize for the confusion.
>
> On Wed, Dec 10, 2014 at 9:37 AM, Nathaniel Smith <njs at pobox.com> wrote:
>
>> On 10 Dec 2014 16:38, "Chris Angelico" <rosuav at gmail.com> wrote:
>> >
>> > Would it be better to clarify that as "generator functions"? Maybe
>> > something like this:
>> >
>> > """
>> > Under this proposal, generator functions and iterators would be
>> > distinct, but related, concepts.  Like the mixing of text and bytes in
>> > Python 2, the mixing of generators and iterators has resulted in
>> > certain perceived conveniences, but proper separation will make bugs
>> > more visible. The distinction is simple: A generator function returns
>> > a generator object. The latter is an iterator, having proper __iter__
>> > and __next__ methods, while the former has neither and does not follow
>> > iterator protocol.
>> > """
>>
>> I find this more confusing than the original, actually, because now it
>> sounds like you're saying that the distinction between a generator function
>> and a generator instance is something new that this PEP is adding, in order
>> to fix all the problems that are being caused by people writing 'for x in
>> genfunc: ...'. Which doesn't make much sense. Like Nick said, it seems to
>> me that the key distinction to emphasize is the distinction between
>> generator function bodies and __next__ method bodies.
>>
>> -n
>>
>> _______________________________________________
>> Python-ideas mailing list
>> Python-ideas at python.org
>> https://mail.python.org/mailman/listinfo/python-ideas
>> Code of Conduct: http://python.org/psf/codeofconduct/
>>
>
>
>
> --
> --Guido van Rossum (python.org/~guido)
>



-- 
--Guido van Rossum (python.org/~guido)
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.python.org/pipermail/python-ideas/attachments/20141210/a317a1a3/attachment.html>
More information about the Python-ideas mailing list