I've read the PEP and understand what's implemented. However there is pretty limited discussion about what the design constraints were and what intended/recommended usage would look like. I'll answer my own question:
1. If all we wanted was a version of TLS that worked in an analogous way extending (synchronous code, threads) to (async code, tasks) then you don't need anything fancy, a simple dictionary backing the "context" will do. This is all that you need to solve the "decimal formatting" problem, for instance. 2. However, the scope of PEP 567 was increased to something greater. It was decided that we want tasks/threads to be able to inherit an existing context. This is a unique feature with no analog in TLS. I believe a motivating use case was for a request/response server that may spawn worker tasks off the main task and want to store request context information in contextvars. 3. Additionally, to continue to have the "decimal formatting" solution work correctly it's necessary that no two tasks/threads are running on the same context. This means "inherting" should mean "running on a copy of". These constraints strongly suggest an interface of: contextvars.get_context() -> Context Context.run_in_copy(func) -> Context Context.async_run_in_copy(coro) -> Context *** NoContext.run method, no copy methods needed either *** So what was the motivation behind having a copy_context() and a non-copying Context.run method? It seems to break the third design constraint allowing you to have multiple threads try and run on the same Context. Nonetheless, "asyncio.run_in_context()" is a direct analog of "Context.run" and should be a clear add to the API from a symmetry point of view. We are already beyond the point where constraint three is being strictly enforced. I'm not sure what argument against this API wouldn't apply to "Context.run()" as well. If it's still a -1 on "asyncio.run_in_context()" what about "asyncio.run_in_context_copy(context, coro) -> Context" that copies the passed context and runs the coroutine in the task using that context? If we go this route maybe we would plan on deprecating Context.run and replacing it with a Context.run_in_copy method? _______________________________________________ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-le...@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/4SYYJEVIV3ZUSVBZIL34EZTIEMBRV533/ Code of Conduct: http://python.org/psf/codeofconduct/
