python-decorator.py

import functools
import inspect

# decorator
def check_role(f):
    # Use this decorator to keep update some attributes of f such as doc string, name ...
    @functools.wraps(f)
    def wrapper(*args, **kwargs):
        # make arguments as a dict, this avoid to check argument which is position or keyword argument
        func_args = inspect.getcallargs(f, *args, **kwargs)
        if func_args.get('user') != 'admin':
            raise Exception('You have not allowed to operate with products')
        return f(*args, **kwargs)
    return wrapper

# class
class Store(object):
    @check_role
    def get_product(self, user, product):
        return self.storage.get(product)
    
    @check_role
    def put_product(self, user, product):
        return self.storage.put(product)