def counter(fn):
count = 0
def inner(*args, **kwargs):
nonlocal count
count += 1
print(f'function fn address at',fn)
print('Function {0} was called {1} times' .format(fn.__name__, count))
return fn(*args, **kwargs) ## argument and keyword argument
return inner
def add(a, b=0):
return a + b
def diff(a, b=0):
return a - b
print(f'function add address at',add)
add = counter(add)
print(f'function add address after counter at',add)
diff = counter(diff)
print(add (1,2))
print(diff(2,3))
print(add(3,4))
print(diff(6,7))
# count and fn are the closure, everytime, the function fn {"add"pass into fn} run, count + 1
# everytime count and (fn <---"add") , inner function's address retained, keep the count and fn as closures.
print(dir(add))
