Backport of inspect
module from Python3.13, supports Python 3.8
- Fully typed with annotations and checked with mypy, PEP561 compatible
- Has backported
bound_arg
parameter ofsignature
andSignature.from_callable
gh-116559 - Has backported
Signature.from_frame
method
pip install inspect313
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.
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)'