[Python-Dev] PEP 590 discussion (original) (raw)

Jeroen Demeyer J.Demeyer at UGent.be
Mon Apr 15 04:38:11 EDT 2019

On 2019-04-14 13:30, Mark Shannon wrote:

PYVECTORCALLARGUMENTSOFFSET exists so that callables that make onward calls with an additional argument can do so efficiently. The obvious example is bound-methods, but classes are at least as important. cls(*args) -> cls.new(cls, *args) -> cls.init(self, *args)

But tp_new and tp_init take the "cls" and "self" as separate arguments, not as part of *args. So I don't see why you need PY_VECTORCALL_ARGUMENTS_OFFSET for this.

The updated minimal implementation now uses const arguments. Code that uses args[-1] must explicitly cast away the const. https://github.com/markshannon/cpython/blob/vectorcall-minimal/Objects/classobject.c#L55

That's better indeed.

Jeroen.

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