How to Retrieve Function Parameter Names in Python?

Retrieving Function Parameter Names in Python

In Python, function parameters are typically defined using placeholder variables. While these variables are explicitly named within the function's definition, they may not be easily accessible when inspecting the function from outside.

inspect.getfullargspec

The inspect module provides a convenient method for obtaining a function's argument list. By calling inspect.getfullargspec(function), where function is the target function, you can retrieve a tuple containing the parameter names.

Example:

<code class="python">def a_method(arg1, arg2):
    pass

print(inspect.getfullargspec(a_method))  # Output: (['arg1', 'arg2'], None, None, None)</code>

This example prints the parameter names ("arg1" and "arg2") as a tuple.

inspect.signature (Python 3.3 )

Since Python 3.3, inspect.signature() provides a more advanced approach to inspecting function signatures. It returns a Signature object that represents the function's parameters, including their types and default values.

Example:

<code class="python">def foo(a, b, c=4, *arglist, **keywords):
    pass

print(inspect.signature(foo))  # Output: <Signature (a, b, c=4, *arglist, **keywords)></code>

Note:

Some callables, such as built-in functions, may not be introspectable in all Python implementations. In such cases, using inspect.getfullargspec() or inspect.signature() may result in a ValueError.

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