On Thu, Oct 12, 2017 at 8:59 AM, Koos Zevenhoven <k7hoven@gmail.com> wrote:
On Thu, Oct 12, 2017 at 6:54 AM, Nick Coghlan <ncoghlan@gmail.com> wrote: [..]
1. Preserve the current behaviour, since we don't have a compelling reason to change its semantics 2. Change the behaviour, in order to gain <end user benefit>
3. Introduce a new context manager that behaves intuitively. My guess is that the two context managers could even be made to interact with each other in a fairly reasonable manner, even if you nest them in different orders. I'm not sure how necessary that is.
Note that this is an independent argument w.r.t. both PEPs. PEP 550 does not propose to change existing decimal APIs. It merely uses decimal to illustrate the problem, and suggests a fix using the new APIs. Although it is true that I plan to propose to use PEP 550 to reimplement decimal APIs on top of it, and so far I haven't seen any real-world examples of code that will be broken because of that. As far as I know—and I've done some research—nobody uses decimal contexts and generators because of the associated problems. It's a chicken and egg problem. Yury