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No validation on erroneous creation of 2 or more parameter variables (VAR_KEYWORD and VAR_POSITIONAL) in inspect.Signature #127610
Description
Bug report
Bug description:
We can create inspect.Signature with two or more variable parameters, but this will be syntactically incorrect when defining the function manually:
import inspect
parameters = [
inspect.Parameter("args", kind=inspect.Parameter.VAR_POSITIONAL),
inspect.Parameter("other_args", kind=inspect.Parameter.VAR_POSITIONAL),
inspect.Parameter("kwargs", kind=inspect.Parameter.VAR_KEYWORD),
inspect.Parameter("other_kwargs", kind=inspect.Parameter.VAR_KEYWORD),
]
signature = inspect.Signature(parameters)
print(signature)OUTPUT:
(*args, *other_args, **kwargs, **other_kwargs)
And naturally we get a syntax error when defining a function with such a signature:
def func(*args, *other_args, **kwargs, **other_kwargs):
...OUTPUT:
File "/home/apostol_fet/inspect_signature.py", line 13
def func(*args, *other_args, **kwargs, **other_kwargs):
^
SyntaxError: * argument may appear only once
Can we add validations for this case in inspect.Signature.__init__?
I would like to send a PR to fix this if it is not intended behavior.
CPython versions tested on:
3.12
Operating systems tested on:
Linux, Windows
Activity
Eclips4 commentedon Dec 4, 2024
cc @serhiy-storchaka
I do think that this check would be useful. We already have a check for situations where user is trying to create a signature with a variadic keyword parameter before a variadic positional parameter:
skirpichev commentedon Dec 5, 2024
Definitely is a bug. Why do we want to produce syntactically incorrect Signature objects?!
serhiy-storchaka commentedon Dec 5, 2024
I agree. There are other checks for the order of parameters, for example positional or keyword parameter is not allowed before positional-only parameter. We should simply add more checks: for var-positional parameter before var-positional parameter and var-keyword parameter before any parameter.
gh-127610: Added validation for more than one var-positional and var-…
serhiy-storchaka commentedon Dec 8, 2024
Thank you for your contribution, @ApostolFet.
pythongh-127610: Added validation for more than one var-positional an…