Decorator.py

# class Decorator(object):

# def __init__(self):
# self.func = func
# print "Created a decorator with: %s" % func

# @Decorator()
# def Foo(n):
# print "Foo: %d" % n
# return 2 * n

# Foo(2)


class double_it(object):

 def __init__(self, f):
 print "__init__()"
 self.f = f

 def __call__(self, *args):
 print "__call__()"
 return 2 * self.f(*args)

@double_it
def multiply(x, y):
 return x * y

print multiply(3, 4)


class cacher(object):

 def __init__(self, func):
 # print "__init__()"
 self.cache = {}
 self.func = func

 def __call__(self, n):
 # print "__call__(%d)" % n
 if n in self.cache:
 return self.cache[n]
 else:
 result = self.func(n)
 self.cache[n] = result
 return result

NUM_CALCS = 0

@cacher
def fibonnaci(n):
 if n == 1 or n== 2:
 return 1
 elif n < 1:
 return None
 else:
 global NUM_CALCS
 NUM_CALCS += 1
 return fibonnaci(n - 1) + fibonnaci(n - 2)

print fibonnaci(20)
print "# calcs: %d" % NUM_CALCS