python利用函数装饰器实现对函数调用次数的跟踪

case1：
>>> class tracer:
    def __init__(self, func):
        self.calls = 0
        self.func = func
    def __call__(self, *args, **keys):
        self.calls += 1
        print('call %s to %s' % (self.calls, self.func.__name__))
        self.func(*args, **keys)

        
# python在定义此函数时，便会将spam作为参数传入__init__
# 类似于spam = tracer(spam)
# 此时的spam已经指向tracer(spam)对象了
>>> @tracer
def spam(a, b, c):
    print(a, b, c)

# 此时调用spam函数，便相当于执行__call__(spam, *(1, 2, 3))
# 这里有运算符重载在起作用。此时的spam对象已经有calls属性了    
>>> spam(1, 2, 3)
call 1 to spam
1 2 3
>>> spam('a', 'b', 'c')
call 2 to spam
a b c
# 可以通过calls属性查看其调用次数
>>> spam.calls
2

import types
 from functools import wraps

def profiled(func):
 ncalls = 0
 @wraps(func)
 def wrapper(*args, *kwargs):
 nonlocal ncalls
 ncalls += 1
 return func(args, **kwargs)
 wrapper.ncalls = lambda: ncalls
 return wrapper

Example
@profiled
 def add(x, y):
 return x + y