详解Python函数式编程之装饰器

import time
# 控制台打印100以内的奇数：
def print_odd():
    for i in range(100):
        if i % 2 == 1:
            print(i)
# 函数闭包：用于增强函数func：给函数func增加统计时间的功能：
def count_time_wrapper(func):
    def improved_func():
        start_time = time.time()
        func()
        end_time = time.time()
        print(f"It takes {end_time - start_time} S to find all the odds in range !!!")
    return improved_func
if __name__ == '__main__':
    # 调用count_time_wrapper增强函数
    print_odd = count_time_wrapper(print_odd)
    print_odd()

def log_wrapper(func):
    """
    闭包,用于增强函数func: 给func增加日志功能
    """
    def improved_func():
        start_time = time.strftime('%Y-%m-%d %H:%M:%S', time.localtime(time.time()))  # 起始时间
        func()  # 执行函数
        end_time = time.strftime('%Y-%m-%d %H:%M:%S', time.localtime(time.time()))  # 结束时间
        print("Logging: func:{} runs from {} to {}".fORMat(func.__name__, start_time, end_time))
    return improved_func

import time
# 函数闭包：用于增强函数func：给函数func增加统计时间的功能：
def count_time_wrapper(func):
    def improved_func():
        start_time = time.time()
        func()
        end_time = time.time()
        print(f"It takes {end_time - start_time} S to find all the odds in range !!!")
    return improved_func
# 控制台打印100以内的奇数：
@count_time_wrapper  # 添加装饰器
def print_odd():
    for i in range(100):
        if i % 2 == 1:
            print(i)
if __name__ == '__main__':
    # 使用  @装饰器（增强函数名） 给当前函数添加装饰器，等价于执行了下面这条语句：
    # print_odd = count_time_wrapper(print_odd)
    print_odd()

def general_wrapper(func):
    def improved_func(*args, **kwargs):
        # 增强函数功能：
        ret = func(*args, **kwargs)
        # 增强函数功能：
        return ret
    return improved_func

import time
# 函数闭包：用于增强函数func：给函数func增加统计时间的功能：
def count_time_wrapper(func):
    # 增强函数：
    def improved_func(*args, **kwargs):
        start_time = time.time()
        result = func(*args, **kwargs)
        end_time = time.time()
        print(f"It takes {end_time - start_time} S to find all the odds in range !!!")
        # 原函数返回值
        return result
    return improved_func
# 计算0-lim奇数之和：
@count_time_wrapper
def count_odds(lim):
    cnt = 0
    for i in range(lim):
        if i % 2 == 1:
            cnt = cnt + i
    return cnt
if __name__ == '__main__':
    result = count_odds(10000000)
    print(f"计算结果为{result}!")

# 装饰器1：
def wrapper1(func1):
    print("set func1")  # 在wrapper1装饰函数时输出
    def improved_func1(*args, **kwargs):
        print("call func1")  # 在wrapper1装饰过的函数被调用时输出
        func1(*args, **kwargs)
        return None
    return improved_func1
# 装饰器2：
def wrapper2(func2):
    print("set func2")  # 在wrapper2装饰函数时输出
    def improved_func2(*args, **kwargs):
        print("call func1")  # 在wrapper2装饰过的函数被调用时输出
        func2(*args, **kwargs)
        return None
    return improved_func2
@wrapper1
@wrapper2
def original_func():
    pass
if __name__ == '__main__':
    original_func()
    print("------------")
    original_func()

@wrapper1
@wrapper2
def original_func():
    pass

original_func = wrapper1(wrapper2(original_func))

import functools
def log_with_param(text):
    def decorator(func):
        @functools.wraps(func)
        def wrapper(*args, **kwargs):
            print('call %s():' % func.__name__)
            print('args = {}'.format(*args))
            print('log_param = {}'.format(text))
            return func(*args, **kwargs)
        return wrapper
    return decorator
@log_with_param("param!!!")
def test_with_param(p):
    print(test_with_param.__name__)
if __name__ == '__main__':
    test_with_param("test")

# 传入装饰器的参数，并接收返回的decorator函数
decorator = log_with_param("param!!!")
# 传入test_with_param函数
wrapper = decorator(test_with_param)
# 调用装饰器函数
wrapper("I'm a param")