Yury Selivanov wrote:
It would be great if you or Greg could show a couple of real-world examples showing the "issue" (with the current PEP 550 APIs/semantics).
Here's one way that refactoring could trip you up. Start with this: async def foo(): calculate_something() #in a coroutine, so we can be lazy and not use a cm ctx = decimal.getcontext().copy() ctx.prec = 5 decimal.setcontext(ctx) calculate_something_else() And factor part of it out (into an *ordinary* function!) async def foo(): calculate_something() calculate_something_else_with_5_digits() def calculate_something_else_with_5_digits(): ctx = decimal.getcontext().copy() ctx.prec = 5 decimal.setcontext(ctx) calculate_something_else() Now we add some more calculation to the end of foo(): async def foo(): calculate_something() calculate_something_else_with_5_digits() calculate_more_stuff() Here we didn't intend calculate_more_stuff() to be done with prec=5, but we forgot that calculate_something_else_ with_5_digits() changes the precision and *doesn't restore it* because we didn't add a context manager to it. If we hadn't been lazy and had used a context manager in the first place, that wouldn't have happened. Summary: I think that skipping context managers in some circumstances is a bad habit that shouldn't be encouraged. -- Greg _______________________________________________ Python-Dev mailing list [email protected] https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com