def get_animal(name=‘dog‘):
    def dog():
        return ‘this is a dog‘
    def cat():
        return ‘this is a cat‘
    # 返回函数对象
    if name == ‘dog‘:
        return dog
    elif name == ‘cat‘:
        return cat
    else:
        return ‘other animal‘
animal = get_animal(‘cat‘)
print(animal)  # <function get_animal.<locals>.cat at 0x104b30d90>
print(animal())

def my_decorator(a_function_to_decorate):
    def wapper_function(*args, **kwargs):
        print(‘Before the function runs‘)
        a_function_to_decorate(*args, **kwargs)
        print(‘After the function runs‘)
    return wapper_function
@my_decorator
def stand_function():
    print(‘stand function runs‘)
stand_function()

# "functools" 可以改变这点
import functools
def bar(func):
    @functools.wraps(func)
    def wrapper():
        return func()
    return wrapper

import logging, time
def create_logger():
    logger = logging.getLogger("example_logger")
    logger.setLevel(logging.INFO)
    # create the logging file handler
    handler = logging.FileHandler(r"./test.log")
    formatter = logging.Formatter(‘%(asctime)s - %(name)s - %(levelname)s - %(message)s‘)
    handler.setFormatter(formatter)
    # add handler to logger object
    logger.addHandler(handler)
    return logger
def exception(logger):
    def decorator(func):
        def wrapper(*args, **kwargs):
            start = time.time()
            try:
                logger.info(‘function runs‘)
                res = func(*args, **kwargs)
                print(‘the function used time: {}‘.format(time.time()-start))
                logger.info(‘function stops‘)
                return res
            except:
                # log the exception
                err = "There was an exception in  "
                err += func.__name__
                logger.exception(err)
                raise Exception
        return wrapper
    return decorator
logger = create_logger()
@exception(logger=logger)
def foo(name=‘foo_function‘):
    print(‘i am {}‘.format(name))
    return True
print(foo())