On 13Oct2017 0941, Yury Selivanov wrote:
On Fri, Oct 13, 2017 at 3:25 AM, Nick Coghlan <ncogh...@gmail.com> wrote:
[..]
However, considering that coroutines are almost always instantiated at the
point where they're awaited, I do concede that creation time context capture
would likely also work out OK for the coroutine case, which would leave
contextlib.contextmanager as the only special case (and it would turn off
both creation-time context capture *and* context isolation).
Actually, capturing context at the moment of coroutine creation (in
PEP 550 v1 semantics) will not work at all. Async context managers
will break.
class AC:
async def __aenter__(self):
pass
^ If the context is captured when coroutines are instantiated,
__aenter__ won't be able to set context variables and thus affect the
code it wraps. That's why coroutines shouldn't capture context when
created, nor they should isolate context. It's a job of async Task.
Then make __aenter__/__aexit__ when called by "async with" an exception
to the normal semantics?
It seems simpler to have one specially named and specially called
function be special, rather than make the semantics more complicated for
all functions.
Cheers,
Steve
_______________________________________________
Python-ideas mailing list
Python-ideas@python.org
https://mail.python.org/mailman/listinfo/python-ideas
Code of Conduct: http://python.org/psf/codeofconduct/
