''' function_arity.py Purpose: To find the arity of a Python function. Author: Vasudev Ram Copyright 2017 Vasudev Ram Web site: https://vasudevram.github.io Blog: https://jugad2.blogspot.com Product store: https://gumroad.com/vasudevram ''' import inspect # Define a few functions with increasing arity: def f0(): pass def f1(a1): pass def f2(a1, a2): pass def f3(a1, a2, a3): pass def f4(a1, a2, a3, a4): pass def main(): # Define a few non-function objects: int1 = 0 float1 = 0.0 str1 = '' tup1 = () lis1 = [] # Test the function arity-finding code with both the functions # and the non-function objects: for o in (f0, f1, f2, f3, f4, int1, float1, str1, tup1, lis1): if not inspect.isfunction(o): print repr(o), 'is not a function' continue n_args = len(inspect.getargspec(o)[0]) if n_args == 0: num_suffix = '(no) args' elif n_args == 1: num_suffix = 'arg' else: num_suffix = 'args' print o.__name__, 'is a function that takes', \ n_args, num_suffix if __name__ == '__main__': main()