Python装饰器

　　＂＂＂     装饰器的本质:     函数闭包的语法糖(没有增加新语法功能,只是一种更方便的写法)     作用:将函数逻辑与辅助函数解耦 ＂＂＂ import time def print_odds():     start = time.time()     for i in range(1000):         if i % 2 == 0:             print(i, end=＂ ＂)     end = time.time()     print(＂ 耗时:＂, end - start) if __name__ == ＂__main__＂:     print_odds() -------------------------------------------------------------------------------------------------- ＂＂＂     第一次解耦 ＂＂＂ import time def run_time(func):     start = time.time()     func()     end = time.time()     print(＂ 耗时:＂, end - start) def print_data():     for i in range(1000):         if i % 2 == 0:             print(i, end=＂ ＂) if __name__ == ＂__main__＂:     run_time(print_data) ---------------------------------------------------------------------------------------------- ＂＂＂     第二次解耦     函数闭包:一个函数，其参数和返回值都是函数     作用:1.用于增强函数的功能;2.面向切面编程(AOP) ＂＂＂ import time def run_time(func):     def wrapper():         start = time.time()         func()         end = time.time()         return print(＂ 耗时:＂, end - start)     return wrapper def print_data():     for i in range(1000):         if i % 2 == 0:             print(i, end=＂ ＂) if __name__ == ＂__main__＂:     print_data= run_time(print_data)     print_data() -------------------------------------------------------------------------------------------------       ＂＂＂     第三次解耦:装饰器     通过装饰器进行函数增强,本质上跟函数闭包的形式一样     装饰器在第一次调用之前被装饰函数进行增强,且只增强一次 ＂＂＂ import time def run_time(func):     def wrapper():         start = time.time()         func()         end = time.time()         return print(＂ 耗时:＂, end - start)     return wrapper @run_time def print_data():     for i in range(1000):         if i % 2 == 0:             print(i, end=＂ ＂) if __name__ == ＂__main__＂:     print_data() -------------------------------------------------------------------------------       ＂＂＂     带参数的装饰器 ＂＂＂ import time def logging(level):     def run_time(func):         def wrapper(*args, **kwargs):             print(＂[{level}]: 装饰的函数是 {func}()＂                   .format(level=level, func=func.__name__))             start = time.time()             func(*args, **kwargs)             end = time.time()             return print(＂ 耗时:＂, end - start)         return wrapper     return run_time @logging(＂INFO＂) def print_data(times):     for i in range(times):         if i % 2 == 0:             print(i, end=＂ ＂) if __name__ == ＂__main__＂:     print_data(10000)