The disadvantages of Python decorators and how to solve them

Disadvantages of 1.python Decorators

Adorners allow us to add additional functionality without changing the way the function or method is invoked;

As shown below, we want to increase the adorner check_is_admin before the method in which to determine whether the user executing the method of the class is the admin user;

Def check_is_admin (f):    def wrapper (*args,**kwargs):        if Kwargs.get (' username ')! = ' Admin ':            raise Exception ("This user isn't allowed to get food")        return F (*args,**kwargs)    return Wrapperclass 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):        self.storage.put (food)

However, the properties of Func_name and Func_doc are lost after the decorator-modified function.

As follows:

def foobar (username= "Someone"): "" "do    Crzay staff.    " " Passprint foobar.func_docprint foobar.func_name Execution result is: do Crzay Staff.foobar

What if I add an adorner to the above function?

Def is_admin (f):    def wrapper (*args,**kwargs):        if Kwargs.get (*args,**kwargs):            Raise Exception ("This user Is isn't allowed to get food ")        return F (*args,**kwargs)    return wrapper@is_admindef foobar (username=" Someone "): "" "do Crazy Staff" ""    passprint foobar.__doc__print foobar.__name__ Execution result is: Nonewrapper

2. Solution

Use Functools's update_wrapper function to solve the problem

As follows:

Def is_admin (f):    def wrapper (*args,**kwargs):        if Kwargs.get (*args,**kwargs):            Raise Exception ("This user Is isn't allowed to get food ")        return F (*args,**kwargs)    return wrapperdef foobar (username=" Someone "):" ""    Crazy Staff "" "    passimport Functoolsfoobar = Functools.update_wrapper (is_admin,foobar) Print Foobar.__name__print Foobar.__doc__ execution results are as follows: Foobardo crazy Staff

The disadvantages of Python decorators and how to solve them