gh-103131: Convert sys.set_asyncgen_hooks to AC

[sobolevn]

Refs #11328

CC @taleinat @serhiy-storchaka as in the original PR

• Issue: sys.getsizeof and sys.set_asyncgen_hooks are not converted to AC #103131

[serhiy-storchaka]

What is the help() output for these functions?

[serhiy-storchaka]

It is an internal refactoring. Such changes usually are not reflected in the NEWS file.

[sobolevn]

Hm, indeed help has gotten even worse. Before:

>>> import sys
>>> help(sys.getsizeof)
Help on built-in function getsizeof in module sys:

getsizeof(...)
    getsizeof(object [, default]) -> int
    
    Return the size of object in bytes.

>>> help(sys.set_asyncgen_hooks)
Help on built-in function set_asyncgen_hooks in module sys:

set_asyncgen_hooks(...)
    set_asyncgen_hooks(* [, firstiter] [, finalizer])
    
    Set a finalizer for async generators objects.

After:

>>> import sys
>>> help(sys.getsizeof)
Help on built-in function getsizeof in module sys:

getsizeof(...)
    Return the size of object in bytes.

>>> help(sys.set_asyncgen_hooks)
Help on built-in function set_asyncgen_hooks in module sys:

set_asyncgen_hooks(...)
    Set a finalizer for async generators objects.

>>> sys.getsizeof.__text_signature__
'($module, /, object, default=<unrepresentable>)'
>>> sys.set_asyncgen_hooks
<built-in function set_asyncgen_hooks>
>>> sys.set_asyncgen_hooks.__text_signature__
'($module, /, firstiter=<unrepresentable>,\n                   finalizer=<unrepresentable>)'

Looks like inspect cannot parse <unrepresentable> as a part of the signature.

>>> inspect.signature(sys.getsizeof)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/sobolev/Desktop/cpython/Lib/inspect.py", line 3322, in signature
    return Signature.from_callable(obj, follow_wrapped=follow_wrapped,
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/sobolev/Desktop/cpython/Lib/inspect.py", line 3066, in from_callable
    return _signature_from_callable(obj, sigcls=cls,
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/sobolev/Desktop/cpython/Lib/inspect.py", line 2558, in _signature_from_callable
    return _signature_from_builtin(sigcls, obj,
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/sobolev/Desktop/cpython/Lib/inspect.py", line 2359, in _signature_from_builtin
    return _signature_fromstr(cls, func, s, skip_bound_arg)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/sobolev/Desktop/cpython/Lib/inspect.py", line 2220, in _signature_fromstr
    raise ValueError("{!r} builtin has invalid signature".format(obj))
ValueError: <built-in function getsizeof> builtin has invalid signature

This part also looks strange:

'($module, /, firstiter=<unrepresentable>,\n                   finalizer=<unrepresentable>)'

Why \n ?

In typeshed we use ... for default values that are hard / impossible to represent.
Can we use the same technique here? So, __text_signature__ would become '($module, /, firstiter=..., finalizer=...)'

[sobolevn]

Ok, I've found the temporary solution. Other similar cases just copy the signature into the docs:

cpython/Objects/odictobject.c

Line 1072 in 20c0f19

od.pop(key[,default]) -> v, remove specified key and return the corresponding value.

New help with it:

>>> import sys
>>> help(sys.getsizeof)
Help on built-in function getsizeof in module sys:

getsizeof(...)
    getsizeof(object [, default]) -> int

    Return the size of object in bytes.

>>> help(sys.set_asyncgen_hooks)
Help on built-in function set_asyncgen_hooks in module sys:

set_asyncgen_hooks(...)
    set_asyncgen_hooks(* [, firstiter] [, finalizer])

    Set a finalizer for async generators objects.

[AlexWaygood]

This now has merge conflicts

[bedevere-bot]

A Python core developer has requested some changes be made to your pull request before we can consider merging it. If you could please address their requests along with any other requests in other reviews from core developers that would be appreciated.

Once you have made the requested changes, please leave a comment on this pull request containing the phrase I have made the requested changes; please review again. I will then notify any core developers who have left a review that you're ready for them to take another look at this pull request.

[vstinner]

Maybe the doc should be modified to use this signature: https://docs.python.org/dev/library/sys.html#sys.set_asyncgen_hooks

Or this docstring should use the doc signature: sys.set_asyncgen_hooks(firstiter, finalizer).

[erlend-aasland]

The docs also read:

Accepts two optional keyword arguments [...]

IMO, the signature in the docs should be updated to reflect the actual implementation.

[sobolevn]

Done in #114385

[vstinner]

Can you please rebase your PR on top of it? There are now merge conflicts.

no longer has merge conflicts

[vstinner]

The help now shows the signature twice. Please remove the second signature:

>>> help(sys.set_asyncgen_hooks)
set_asyncgen_hooks(firstiter=<unrepresentable>,
                   finalizer=<unrepresentable>)
    set_asyncgen_hooks([firstiter] [, finalizer])

    Set a finalizer for async generators objects.

>>> help(sys.getsizeof)
getsizeof(object, default=<unrepresentable>)
    getsizeof(object [, default]) -> int

    Return the size of object in bytes.

[vstinner]

I suggest to use a longer name rather than a shorter one:

Suggested change

	default as dflt: object = NULL
	default as default_size: object = NULL

[erlend-aasland]

That would make the diff unnecessary bigger. IMO, it is better to align with the current naming.

[sobolevn]

The sys.getsizeof change is incorrect. I can still convert sys.set_asyncget_hooks and change the defaults from NULL to Py_None, looks like that this will be valid.

[sobolevn]

Here's the new help() output:

» ./python.exe
Python 3.13.0a5+ (heads/issue-103131:c0086505210, Mar 20 2024, 13:48:58) [Clang 15.0.0 (clang-1500.0.40.1)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import sys
>>> help(sys.set_asyncgen_hooks)
Help on built-in function set_asyncgen_hooks in module sys:

set_asyncgen_hooks(firstiter=None, finalizer=None)
    Set a finalizer for async generators objects.

None is supported and even tested here:

cpython/Lib/test/test_sys.py

Lines 1766 to 1790 in 8182319

	def test_asyncgen_hooks(self):
	old = sys.get_asyncgen_hooks()
	self.assertIsNone(old.firstiter)
	self.assertIsNone(old.finalizer)
	firstiter = lambda *a: None
	sys.set_asyncgen_hooks(firstiter=firstiter)
	hooks = sys.get_asyncgen_hooks()
	self.assertIs(hooks.firstiter, firstiter)
	self.assertIs(hooks[0], firstiter)
	self.assertIs(hooks.finalizer, None)
	self.assertIs(hooks[1], None)
	finalizer = lambda *a: None
	sys.set_asyncgen_hooks(finalizer=finalizer)
	hooks = sys.get_asyncgen_hooks()
	self.assertIs(hooks.firstiter, firstiter)
	self.assertIs(hooks[0], firstiter)
	self.assertIs(hooks.finalizer, finalizer)
	self.assertIs(hooks[1], finalizer)
	sys.set_asyncgen_hooks(*old)
	cur = sys.get_asyncgen_hooks()
	self.assertIsNone(cur.firstiter)
	self.assertIsNone(cur.finalizer)

So, this now should be a simple change :)

[sobolevn]

Ok, I've found this branch:

else if (finalizer == Py_None && _PyEval_SetAsyncGenFinalizer(NULL) < 0) {
        return NULL;
    }

Looks like this PR is not correct either. It is better to close it.

[vstinner]

Looks like this PR is not correct either. It is better to close it.

If someone wants to continue the work, I suggest to leave Argument Clinic aside, and start by fixing the implementation and the signature to prepare the API for Argument Clinic.