On Mon, Aug 28, 2017 at 7:19 AM, Stefan Krah <ste...@bytereef.org> wrote: > On Sun, Aug 27, 2017 at 11:19:20AM -0400, Yury Selivanov wrote: >> On Sun, Aug 27, 2017 at 6:08 AM, Stefan Krah <ste...@bytereef.org> wrote: >> > On Sat, Aug 26, 2017 at 04:13:24PM -0700, Nathaniel Smith wrote: >> >> It's perfectly reasonable to have a script where you call >> >> decimal.setcontext or np.seterr somewhere at the top to set the >> >> defaults for the rest of the script. >> > >> > +100. The only thing that makes sense for decimal is to change >> > localcontext() >> > to be automatically async-safe while preserving the rest of the semantics. >> >> TBH Nathaniel's argument isn't entirely correct. >> >> With the semantics defined in PEP 550 v4, you still can set decimal >> context on top of your file, in your async functions etc. >> >> and this: >> >> def bar(): >> decimal.setcontext(ctx) >> >> def foo(): >> bar() >> # use decimal with context=ctx > > Okay, so if I understand this correctly we actually will not have dynamic > scoping for regular functions: bar() has returned, so the new context > would not be found on the stack with proper dynamic scoping.
Correct. Although I would avoid associating PEP 550 with dynamic scoping entirely, as we never intended to implement it. [..] > What about this? > > async def bar(): > setcontext(Context(prec=1)) > for i in range(10): > await asyncio.sleep(1) > yield i > > async def foo(): > async for i in bar(): > # ctx.prec=1? > print(Decimal(100) / 3) > > > > I'm searching for some abstract model to reason about the scopes. Whatever is set in coroutines, generators, and async generators does not leak out. In the above example, "prec=1" will only be set inside "bar()", and "foo()" will not see that. (Same will happen for a regular function and a generator). Yury _______________________________________________ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
