2.6 装饰器

最新推荐文章于 2025-09-16 08:00:00 发布

原创最新推荐文章于 2025-09-16 08:00:00 发布 · 174 阅读

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#装饰器

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文章介绍了Python中装饰器的三种使用方式：1)直接调用函数；2)返回包装函数，需要手动调用；3)带参数的装饰器，展示了如何在装饰器中传递参数并影响被装饰的函数。这些例子主要用于测量和打印函数的执行时间。

1、普通用法

import time


def timer(fun):
    start = time.time()
    fun()
    end = time.time()
    print(f'function:{fun.__name__},duration:', end=f'{end - start}\n')


@timer
def a():
    pass


@timer
def b():
    time.sleep(3)
    pass

装饰器timer中直接调用了fun()，所以上述代码直接运行即可

等同于

import time


def timer(fun):
    start = time.time()
    fun()
    end = time.time()
    print(f'function:{fun.__name__},duration:', end=f'{end - start}\n')


def a():
    pass


timer(a)

2、返回函数

import time


def timer(fun):
    def wrapper(*args, **kwargs):
        start = time.time()
        fun()
        end = time.time()
        print(f'function:{fun.__name__},duration:', end=f'{end - start}\n')
    return wrapper


@timer
def a():
    pass


@timer
def b():
    time.sleep(3)
    pass


a()
b()

import time


def timer(fun):
    def wrapper(*args, **kwargs):
        start = time.time()
        fun(*args)
        end = time.time()
        print(f'function:{fun.__name__},duration:', end=f'{end - start}\n')
    return wrapper


@timer
def a(*args):
    print(args)
    pass


@timer
def b(*args):
    print(args)
    time.sleep(3)
    pass


a(1)
b(2)

装饰器返回了一个函数，所以需要手工调用

上述代码等同于

import time


def timer(fun):
    def wrapper(*args, **kwargs):
        start = time.time()
        fun(*args)
        end = time.time()
        print(f'function:{fun.__name__},duration:', end=f'{end - start}\n')

    return wrapper


def a(*args):
    print(args)
    pass


c = timer(a)
# c是返回的wrapper方法
c('1', '2')
# 当a()被装饰器装饰时,主动调用a()时，其实已经被替换为装饰器返回的方法

3、有参数装饰器

import time


def timer(level):
    def decorator(fun):
        def wrapper(*args, **kwargs):
            start = time.time()
            fun(level)
            end = time.time()
            print(f'function:{fun.__name__},duration:', end=f'{end - start}\n')
        return wrapper
    return decorator


@timer('1')
def a(*args):
    print(args)
    pass


@timer('2')
def b(*args):
    print(args)
    time.sleep(3)
    pass


a()
b()

import time


def timer(level):
    def decorator(fun):
        def wrapper(*args, **kwargs):
            return fun(level, *args, **kwargs)

        return wrapper

    return decorator


@timer('level')
def a(*args):
    print(args)
    pass


@timer('level')
def b(*args):
    print(args)
    time.sleep(3)
    pass


a(1, 2, 3, 4, {"a": 1})
b(2, 3, 4, 5)