Abusing python defaults

statichack.py

# Abusing python default initialization to create static variables
def pompom(arg, static={'counter': 0}):
    static['counter'] += 1
        
    print("Yup %d, %d") % (arg, static['counter'])
pompom(8)
pompom(42)
"""
Yup 8, 1
Yup 42, 2
"""

class Static(object):
    def __init__(self, **kwargs):
        for k, v in kwargs.items():
            setattr(self, k, v)

def another(arg, static=Static(counter=0)):
    static.counter += 1
        
    print("Yup (again) %d, %d") % (arg, static.counter)


another(8)
another(80)

"""
Yup (again) 8, 1
Yup (again) 80, 2
"""