On 2018-04-16 02:32, Raymond Hettinger wrote:

I don't think that confidence is warranted. The world of Python is very large. When public APIs (such as that in the venerable types module) get changed, is virtually assured that some code will break.

Yes, *some* code will break, I never denied that. I just think that there is not much existing code which needs to distinguish between different kinds of methods, such that not much code will break. And if existing code does need to make that distinction, the reason for it might go away after PEP 575 (this is what Nick Coghlan also alluded to). The hard question is whether the expected breakage is bad enough to reject this PEP. This is my first PEP, so I honestly don't have a good idea how high the bar for backwards compatibility is. Jeroen.