Python - Get Function Signature

Python Server Side Programming Programming

Understanding function signatures in Python is essential for unraveling the inner workings of functions. The inspect module offers a range of methods to retrieve signatures, allowing you to analyze parameters, access data types, and determine default values. By exploring these techniques, you can gain valuable insights that enhance code readability, maintainability, and documentation. So, dive into the world of function signatures and unlock a deeper understanding of your Python code.

Using inspect Method

The inspect method provides a powerful way to retrieve the function signatures. This method enables us to access detailed information about a function's parameters, data types, default values, and more. This helps the developers know better about the function, requirements, and properties.

Example

We first imported the inspect module using the import statement in the following code. Next, we created a void function named my_function which takes a couple of arguments and their hints. We created an object with the signature method of inspect module and passed the my_functionn as the argument. Next, we used the parameters method to access the details of the parameters. We iterated over the return value and printed it.

import inspect

def my_function(arg1: int, arg2: str, *args: int, **kwargs: float) -> bool:
    pass

signature = inspect.signature(my_function)
params = signature.parameters

for name, param in params.items():
    print(f"Parameter: {name}")
    print(f"Type: {param.annotation}")
    print(f"Default Value: {param.default}")
    print(f"Kind: {param.kind}")
    print("---")

Output

Parameter: arg1
Type: 
Default Value: 
Kind: POSITIONAL_OR_KEYWORD
---
Parameter: arg2
Type: 
Default Value: 
Kind: POSITIONAL_OR_KEYWORD
---
Parameter: args
Type: 
Default Value: 
Kind: VAR_POSITIONAL
---
Parameter: kwargs
Type: 
Default Value: 
Kind: VAR_KEYWORD
---

Using the inspect module's getfullargspec function

The getfullargspec function of the inspect module is another method that we can use to retrieve comprehensive information about the function's arguments. It provides a detailed analysis of both the positional and keyword arguments. It also supports the variable arguments and keyword arguments.

Example

In the following code, we imported the inspect library and defined a user-defined function named my_function. Next, we created an object named argspec using the getfullargspec method. We passed our function as the argument. Next, we used the zip method to combine the argument details and the annotation values and for the loop to iterate and print the results.

import inspect

def my_function(arg1: int, arg2: str, *args: int, **kwargs: float) -> bool:
    pass

argspec = inspect.getfullargspec(my_function)

for name, annotation in zip(argspec.args, argspec.annotations.values()):
    print(f"Parameter: {name}")
    print(f"Type: {annotation}")
    print("---")

Output

Parameter: arg1
Type: <class 'bool'>
---
Parameter: arg2
Type: <class 'int'>
---

Conclusion

Asif Rahaman

Updated on: 18-Jul-2023

659 Views

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