装饰器检查参数

test_deco_check_args.py

def check_is_admin(f):
    def wapper(*args, **kwargs):
        if kwargs.get('username') != 'admin':
            raise Exception('This user is not allowed to get')
        return f(*args, **kwargs)

    return wapper


class Store(object):
    @check_is_admin
    def get_food(self, username, food):
        return self.storage.get(food)

    @check_is_admin
    def put_food(self, username, food):
        return self.storage.put(food)

test_deco_check_args2.py

import functools

#改进版， 原来装饰器创建的新函数 会缺少 原函数的很多属性， functools提供了一个工具， 将这些属性加回来。

def check_is_admin(f):
    @functools.wraps(f)
    def wapper(*args, **kwargs):
        if kwargs.get('username') != 'admin':
            raise Exception('This user is not allowed to get')
        return f(*args, **kwargs)

    return wapper


class Store(object):
    @check_is_admin
    def get_food(self, username, food):
        return self.storage.get(food)

    @check_is_admin
    def put_food(self, username, food):
        return self.storage.put(food)