On 2018-05-19 11:15, mark wrote:
PEP 576 aims to fulfill the same goals as PEP 575
(this is a copy of my comments on GitHub before this PEP was official)
Most importantly, changing bound methods of extension types from builtin_function_or_method to bound_method will yield a performance loss. It might be possible to mitigate this somewhat by adding specific optimizations for calling bound_method. However, that would add extra complexity and it will probably still be slower than the existing code.
And I would also like to know whether it will be possible for custom built-in function subclasses to implement __get__ to change a function into a method (like Python functions) and whether/how the LOAD_METHOD opcode will work in that case.
When I want "introspection support", that goes beyond the call signature. Also inspect.getfile should be supported. Currently, that simply raises an exception for built-in functions.
I think it's important to specify the semantics of inspect.isfunction. Given that you don't mention it, I assume that inspect.isfunction will continue to return True only for Python functions. But that way, these new function classes won't behave like Python functions.
fully backwards compatible.
I wonder why you think it is "fully backwards compatible". Just like PEP 575, you are changing the classes of certain objects. I think it's fairer to say that both PEP 575 and PEP 576 might cause minor backwards compatibility issues. I certainly don't think that PEP 576 is significantly more backwards compatible than PEP 575.
PS: in your PEP, you write "bound_method" but I guess you mean "method". PEP 575 proposes to rename "method" to "bound_method".