On Wed, Sep 6, 2017 at 10:07 AM, Greg Ewing <greg.ew...@canterbury.ac.nz> wrote:
> Yury Selivanov wrote: > >> Greg, have you seen this new section: >> https://www.python.org/dev/peps/pep-0550/#should-yield-from- >> leak-context-changes >> > > That section seems to be addressing the idea of a generator > behaving differently depending on whether you use yield-from > on it. > Regarding this, I think yield from should have the same semantics as iterating over the generator with next/send, and PEP 555 has no issues with this. > > I never suggested that, and I'm still not suggesting it. > > The bottomline is that it's easier to >> reason about context when it's guaranteed that context changes are >> always isolated in generators no matter what. >> > > I don't see a lot of value in trying to automagically > isolate changes to global state *only* in generators. > > Under PEP 550, if you want to e.g. change the decimal > context temporarily in a non-generator function, you're > still going to have to protect those changes using a > with-statement or something equivalent. I don't see > why the same thing shouldn't apply to generators. > > > It seems to me that it will be *more* confusing to give > generators this magical ability to avoid with-statements. > > > Exactly. To state it clearly: PEP 555 does not have this issue. ––Koos -- + Koos Zevenhoven + http://twitter.com/k7hoven +
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