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

Oscar Benjamin oscar.j.benjamin at gmail.com
Thu Oct 17 20:55:38 CEST 2013

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, redirectstdout).

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

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