[Python-Dev] PEP 550 v4
stefan at bytereef.org
Mon Aug 28 11:52:15 EDT 2017
On Mon, Aug 28, 2017 at 11:23:12AM -0400, Yury Selivanov wrote:
> On Mon, Aug 28, 2017 at 7:19 AM, Stefan Krah <stefan at bytereef.org> wrote:
> > 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.
Good, I agree it does not make sense.
> > 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).
But the state "leaks in" as per your previous example:
async def bar():
# use decimal with context=ctx
async def foo():
IMHO it shouldn't with coroutine-local-storage (let's call it CLS). So,
as I see it, there's still some mixture between dynamic scoping and CLS
because it this example bar() is allowed to search the stack.
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