[Python-Dev] PEP 575: Unifying function/method classes

[Jeroen Demeyer]

On 2018-04-14 23:14, Guido van Rossum wrote:
> That actually sounds like a pretty big problem. I'm sure there is lots
> of code that doesn't *just* duck-type nor calls inspect but uses
> isinstance() to decide how to extract the desired information.

I have been thinking about this some more...

One solution to improve backwards compatibility would be to duplicate 
some classes. For example, make a separate class for bound methods in 
extension types, which would be literally a duplicate of the existing 
types.MethodType class (possibly with a different name). In other words, 
a bound method of an extension type would work exactly the same way as 
an existing bound method but it would artificially be a different class 
for the benefit of non-duck-typing.