[Python-Dev] PEP 479: Change StopIteration handling inside generators

[Guido van Rossum]

On Tue, Nov 25, 2014 at 9:49 AM, Chris Angelico <rosuav at gmail.com> wrote:

> On Wed, Nov 26, 2014 at 4:45 AM, Isaac Schwabacher
> <ischwabacher at wisc.edu> wrote:
> > Yield can also raise StopIteration, if it's thrown in. The current
> interaction of generator.throw(StopIteration) with yield from can't be
> emulated under the PEP's behavior, though it's not clear that that's a
> problem.
> >
>
> Hrm. I have *absolutely* no idea when you would use that, and how
> you'd go about reworking it to fit this proposal. Do you have any
> example code (production or synthetic) which throws StopIteration into
> a generator?
>

Sounds like a good one for the obfuscated Python contest. :-)

Unless the generator has a try/except surrounding the yield point into
which the exception is thrown, it will bubble right out, and PEP 479 will
turn this into a RuntimeError. I'll clarify this in the PEP (even though it
logically follows from the proposal) -- I don't think there's anything to
worry about.

-- 
--Guido van Rossum (python.org/~guido)
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