On 25 August 2017 at 23:36, Yury Selivanov <yselivanov...@gmail.com> wrote: > On Fri, Aug 25, 2017 at 9:23 AM, Nick Coghlan <ncogh...@gmail.com> wrote: > [..] >> And while PEP 550 doesn't handle the stream redirection case natively >> (since it doesn't allow for suspend/resume callbacks the way PEP 525 >> does), it at least allows for the development of a context-aware >> output stream wrapper API where: > > PEP 525 can't handle streams redirection -- it can do it only for > single-threaded programs.
Good point, whereas the hypothetical context-aware wrapper I proposed would be both thread-safe (since the process global would be changed once before the program went multi-threaded and then left alone) *and* potentially lower overhead (one context local lookup per stream attribute access, rather than a global state change every time a frame was suspended or resumed with a stream redirected) > sys.stdout/stderr/stdin are global variables, that's how the API is > specified. API users assume that the change is process-wide. Yeah, I wasn't suggesting any implicit changes to the way those work. However, it does occur to me that if we did add a new "contextlocals" API, then: 1. It could offer context-aware wrappers for stdin/stdout/stderr 2. If could offer context-aware alternatives to the stream redirection context managers in contextlib That approach would work even better than replacing sys.stdin/out/err themselves with wrappers since the wrappers wouldn't be vulnerable to being overwritten by other code that mutated the sys module. Anyway, that's not a serious proposal right now, but I do think it's decent validation of the power and flexibility of the proposed implicit state management model. Cheers, Nick. -- Nick Coghlan | ncogh...@gmail.com | Brisbane, Australia _______________________________________________ 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
