How to Check if a Variable Refers to a Function in Python?

Detecting Function Variables in Python

You have a variable named "x" and want to determine if it points to a function. While checking the type of "x" shows it's a function, attempting to use isinstance(x, function) fails. This is where callable() comes in handy.

Python 2.x and Python 3.2 :

callable(x)

Python 3.x before 3.2:

hasattr(x, '__call__')

Previous approaches like types.FunctionTypes or inspect.isfunction have limitations. They return False for non-Python functions, such as builtins, which are implemented in C.

Instead of checking the type or fitting into a container, it's best to "ask" the object if it can be called by looking for the call attribute. This ensures accurate identification of functions, regardless of their implementation.

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