'''
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()
