On 09/07/2017 03:37 AM, Greg Ewing wrote:
If I understand correctly, instead of using a context manager, your fractions example could be written like this:def fractions(precision, x, y): ctx = decimal.getcontext().copy() decimal.setcontext(ctx) ctx.prec = precision yield MyDecimal(x) / MyDecimal(y) yield MyDecimal(x) / MyDecimal(y ** 2) and it would work without leaking changes to the decimal context, despite the fact that it doesn't use a context manager or do anything else to explicitly put back the old context.
The disagreement seems to be whether a LogicalContext should be created implicitly vs explicitly (or opt-out vs opt-in). As a user trying to track down a decimal context change not propagating, I would not suspect the above code of automatically creating a LogicalContext and isolating the change, whereas Greg's context manager version is abundantly clear.
The implicit vs explicit argument comes down, I think, to resource management: some resources in Python are automatically managed (memory), and some are not (files) -- which type should LCs be?
-- ~Ethan~ _______________________________________________ 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
