[Python-Dev] On suppress()'s trail blazing (was Re: cpython: Rename contextlib.ignored() to contextlib.ignore())

[Oscar Benjamin]

On 17 October 2013 19:40, Xavier Morel <python-dev at masklinn.net> wrote:
> I think there's already a significant split between context managers
> which handle the lifecycle of a local resource (file, transaction) and
> those which purport to locally alter global-ish state (cwd,
> decimal.localcontext, logging.captureWarnings, redirect_stdout).
>
> And the latter worries me (much more than the very localized behavior of
> suppress) because I don't see any way to implement them safely and
> correctly when mixing it with coroutines in today's Python (some of them
> aren't even thread-safe), all of that while I expect coroutines will see
> significantly more use in the very near future with yield from and
> tulip's promotion of coroutine-style async.

I maybe misunderstanding how the  coroutine-style async works but I
would have thought that it would be as simple as: don't use
global-state-restoring-context-managers around statements that yield
control (it would be simpler if there was a good term for describing
that kind of CM). That's simpler to implement and computationally
cheaper than e.g. the thread-local state used by the decimal module.


Oscar