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inspect313

test Python Version

Backport of inspect module from Python3.13, supports Python 3.8+

Features

  • Fully typed with annotations and checked with mypy, PEP561 compatible
  • Has backported bound_arg parameter of signature and Signature.from_callable gh-116559
  • Has backported Signature.from_frame method

Installation

pip install inspect313

Examples

Replace inspect.getfullargspec with inspect.signature

getfullargspec is an old way of getting the function signature. It is deprecated since Python 3.13, and new bound_arg: bool = False argument was introduced in the same version.

However, this change was not backported, so users of older Python versions need this package to have the same functionality.

Here's how getfullargspec is different from regular signature call:

  • the self / cls parameter is always reported, even for bound methods
>>> import inspect

>>> class A:
...    def method(self, arg: int) -> None: ...

>>> inspect.getfullargspec(A().method)
FullArgSpec(args=['self', 'arg'], varargs=None, varkw=None, defaults=None, kwonlyargs=[], kwonlydefaults=None, annotations={'return': None, 'arg': <class 'int'>})

>>> # signature() produces a different result:
>>> inspect.signature(A().method)
<Signature (arg: int) -> None>
  • wrapper chains defined by __wrapped__ not unwrapped automatically
>>> import functools

>>> def some_decorator(f):
...     @functools.wraps(f)
...     def wrapper(*args, **kwargs):
...         return f(*args, **kwargs)
...     return wrapper

>>> @some_decorator
... def func(a: int, /, b: str) -> None: ...

>>> inspect.getfullargspec(func)
FullArgSpec(args=[], varargs='args', varkw='kwargs', defaults=None, kwonlyargs=[], kwonlydefaults=None, annotations={'return': None})

>>> # signature() produces a different result:
>>> inspect.signature(func)
<Signature (a: int, /, b: str) -> None>

Here's how you can migrate, these results will be in line with getfullargspec:

>>> import inspect313

>>> inspect313.signature(
...    A().method,
...    bound_arg=True,
...    follow_wrapped=False,
... )
<Signature (self, arg: int) -> None>

>>> inspect313.signature(
...    func,
...    bound_arg=True,
...    follow_wrapped=False,
... )
<Signature (*args, **kwargs) -> None>

However, consider migrating to just using inspect.signature, since it produces more correct results in a general case.

Replace inspect.getargvalues with inspect.Signature.from_frame

getargvalues was used to create signature-like objects from frame objects. But, it didn't really support all features of modern functions.

This is why Python 3.13 introduced inspect.Signature.from_frame public constructor and getargvalues and formatargvalues were deprecated.

Here's how it worked before:

>>> import inspect

>>> def func(a: int = 0, /, b: int = 1, *, c: int = 2):
...     return inspect.currentframe()

>>> frame = func()
>>> # notice that pos-only and kw-only args are not supported properly:
>>> inspect.formatargvalues(*inspect.getargvalues(frame))
'(a=0, b=1, c=2)'

Here's how to replace it with modern API:

>>> from inspect313 import Signature

>>> str(Signature.from_frame(frame))
'(a=0, /, b=1, *, c=2)'

License

MIT