Readthedocs
python-forge.readthedocs.io › en › latest › signature.html
Signatures, parameters and return types — forge 18.6.0 documentation
Python callables have a signature: the interface which describes what arguments are accepted and (optionally) what kind of value is returned. ... The function func (above) has the signature (a, b, c). We know that it requires three arguments, one for a, b and c.
Python
peps.python.org › pep-0362
PEP 362 – Function Signature Object | peps.python.org
August 21, 2006 - The new metadata object is intended solely to make function introspection easier for Python programmers. A Signature object represents the call signature of a function and its return annotation.
Videos
00:10
Understanding function signatures - YouTube
01:48
Understanding Function Signatures in Python - YouTube
28:05
Things (Almost) No One Thinks About When Designing Functions in ...
01:15
How to Read Function Signatures in Python Documentation - YouTube
01:20
Understanding Function Signature in Python - YouTube
04:44
Docstrings in Python - YouTube
Python Like You Mean It
pythonlikeyoumeanit.com › Module2_EssentialsOfPython › Functions.html
Basics of Functions — Python Like You Mean It
<function signature> specifies the input arguments to the function, and may be left blank if the function does not accept any arguments (the parentheses must still be included, but will not encapsulate anything). The documentation string (commonly referred to as a “docstring”) may span ...
GeeksforGeeks
geeksforgeeks.org › python › python-get-function-signature
Get Function Signature - Python - GeeksforGeeks
July 15, 2025 - A function signature in Python defines the name of the function, its parameters, their data types , default values and the return type. It acts as a blueprint for the function, showing how it should be called and what values it requires.
Python.org
discuss.python.org › documentation
Helping people understand function signature syntax - Documentation - Discussions on Python.org
July 20, 2024 - (Bringing a conversation about how to explain slash and star in function signatures from another post which talked about using tags, and a GitHub issue which experimented with tabs to show simplified vs complete signatures). Another possibility is to add a “help” icon next to signatures.
Python
docs.python.org › 3 › library › inspect.html
inspect — Inspect live objects — Python 3.14.5rc1 documentation
Pass False to get a signature of callable specifically (callable.__wrapped__ will not be used to unwrap decorated callables.) Changed in version 3.10: The globals, locals, and eval_str parameters were added. Changed in version 3.14: The annotation_format parameter was added. ... Some callables may not be introspectable in certain implementations of Python. For example, in CPython, some built-in functions defined in C provide no metadata about their arguments.
Chipx86
chipx86.blog › 2025 › 07 › 12 › a-crash-course-on-python-function-signatures-and-typing
A crash course on Python function signatures and typing
August 8, 2025 - If a function has __signature__ defined, it will reference this (at least in CPython), and this gives highly-dynamic code the ability to patch signatures at runtime. (If you’re curious, here’s exactly how it works). There are a few places where knowing the signature can be useful, such as: Automatically-crafting documentation (Sphinx does this)
Readthedocs
funcsigs.readthedocs.io › en › 0.4
Introducing funcsigs — funcsigs 0.4 documentation
PEP 362 - Function Signature Object. The detailed specification, implementation details and examples. funcsigs is a derived work of CPython under the terms of the PSF License Agreement. The original CPython inspect module, its unit tests and documentation are the copyright of the Python Software ...
IPython
ipython.org › ipython-doc › 3 › api › generated › IPython.utils.signatures.html
Module: utils.signatures — IPython 3.2.1 documentation
Constructs Signature from the given list of Parameter objects and ‘return_annotation’. All arguments are optional. ... Get a BoundArguments object, that maps the passed args and kwargs to the function’s signature.
Boostorg
boostorg.github.io › python › doc › html › reference › function_invocation_and_creation › function_documentation.html
Function documentation
Boost.Python supports docstrings with automatic appending of Pythonic and C++ signatures. This feature is implemented by class function_doc_signature_generator. The class uses all of the overloads, supplied arg names and default values, as well as the user-defined docstrings, to generate documentation for a given function.
Python documentation
docs.python.org › 3 › library › functions.html
Built-in Functions — Python 3.14.5rc1 documentation
February 27, 2026 - This function is added to the built-in namespace by the site module. Changed in version 3.4: Changes to pydoc and inspect mean that the reported signatures for callables are now more comprehensive and consistent.
TutorialsPoint
tutorialspoint.com › python-get-function-signature
Python - Get Function Signature
July 18, 2023 - import inspect def calculate_area(length: float, width: float = 1.0) -> float: """Calculate rectangle area.""" return length * width def document_function(func): sig = inspect.signature(func) print(f"Function: {func.__name__}") print(f"Signature: {sig}") print(f"Return type: {sig.return_annotation}") for name, param in sig.parameters.items(): has_default = param.default != inspect.Parameter.empty default_info = f" (default: {param.default})" if has_default else "" print(f" {name}: {param.annotation}{default_info}") document_function(calculate_area)
Top answer 1 of 3
22
In general the signature of a function is defined by the number and type of input arguments the function takes and the type of the result the function returns.
As an example in C++ consider the following function:
int multiply(int x, int y){
return x*y;
}
The signature of that function, described in an abstract way would be the set {int, int, int}.
As Python is a weakly typed language in general the signature is only given by the amount of parameters. But in newer Python versions type hints were introduced which clarify the signature:
def multiply(x: int, y: int) -> int:
return x*y
2 of 3
4
The signature indicates the names and types of the input arguments, and (with type annotations) the type of the returned result(s) of a function or method.
This is not particular to Python, though the concept is more central in some other languages (like C++, where the same method name can exist with multiple signatures, and the types of the input arguments determine which one will be called).
Top answer 1 of 9
277
import inspect
def foo(a, b, x='blah'):
pass
print(inspect.signature(foo))
# (a, b, x='blah')
Python 3.5+ recommends inspect.signature().
2 of 9
61
Arguably the easiest way to find the signature for a function would be help(function):
>>> def function(arg1, arg2="foo", *args, **kwargs): pass
>>> help(function)
Help on function function in module __main__:
function(arg1, arg2='foo', *args, **kwargs)
Also, in Python 3 a method was added to the inspect module called signature, which is designed to represent the signature of a callable object and its return annotation:
>>> from inspect import signature
>>> def foo(a, *, b:int, **kwargs):
... pass
>>> sig = signature(foo)
>>> str(sig)
'(a, *, b:int, **kwargs)'
>>> str(sig.parameters['b'])
'b:int'
>>> sig.parameters['b'].annotation
<class 'int'>
The Hitchhiker's Guide to Python
docs.python-guide.org › writing › documentation
Documentation — The Hitchhiker's Guide to Python
Extended description of function. Parameters ---------- arg1 : int Description of arg1 arg2 : str Description of arg2 Returns ------- int Description of return value """ return 42 · The sphinx.ext.napoleon plugin allows Sphinx to parse this style of docstrings, making it easy to incorporate NumPy style docstrings into your project. At the end of the day, it doesn’t really matter what style is used for writing docstrings; their purpose is to serve as documentation for anyone who may need to read or make changes to your code.
Delft Stack
delftstack.com › home › howto › python › python function signature
How to Get Function Signature | Delft Stack
March 11, 2025 - This tutorial explores how to get function signatures in Python, providing clear methods and examples for understanding function call details. Learn to use the inspect module, __doc__ attribute, and help function to retrieve valuable information about functions.
AskPython
askpython.com › home › understanding and utilizing function signatures in python
Understanding and Utilizing Function Signatures in Python - AskPython
June 30, 2023 - In Python, a function signature provides crucial information about the types of parameters that a function can accept and the type of data it returns. The signature() function from the inspect module is used to determine the function signature, ...
Pyo3
pyo3.rs › main › function › signature
Function signatures - PyO3 user guide
This behaviour can be configured by the #[pyo3(signature = (...))] option which allows writing a signature in Python syntax. This section of the guide goes into detail about use of the #[pyo3(signature = (...))] option and its related option #[pyo3(text_signature = "...")] For example, below is a function that accepts arbitrary keyword arguments (**kwargs in Python syntax) and returns the number that was passed:
Real Python
realpython.com › lessons › view-function-signatures
View Function Signatures (Video) – Real Python
When you type an opening parenthesis to call a function or method in bpython, it will display the corresponding function signature with its formal parameters and their default values.
Published October 31, 2023
Python documentation
docs.python.org › 3 › library › typing.html
typing — Support for type hints — Python 3.14.5rc1 documentation
February 24, 2026 - # Invalid use of AnyStr: # The type variable is used only once in the function signature, # so cannot be "solved" by the type checker def greet_bad(cond: bool) -> AnyStr: return "hi there!" if cond else b"greetings!" # The better way of annotating this function: def greet_proper(cond: bool) -> str | bytes: return "hi there!" if cond else b"greetings!"