[Python-Dev] PEP: 576 Title: Rationalize Built-in function classes
J.Demeyer at UGent.be
Sun May 20 15:26:00 EDT 2018
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".
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