Python Decorator Inheritance issue

Question

class Foo():
    help_message = ""

    def Help_Decorator(func):
        def wrapper(data, context, caller):
            try:
                if data[0] == "help":
                    return(help_message) #<--- cannot access this locally
                else:
                    return func(data,context,caller)
            except:
                return func(data,context,caller)
    return wrapper

class Bar(Foo):
    help_message = "A real help message!"
    @foo.Help_Decorator
    def Run(data,context,caller):
        pass

How can I access Bar's help_message from within my Help_Decorator without passing it as a parameter in Run ?

Answer 1

Since Run is an instance method, data is a Bar instance. Normally this would be called self by convention, but giving it a different name doesn't change the semantics of the function call.

You should therefore be able to access data.help_message in your wrapper function. (I would also expect that data[0] gives you a TypeError unless Bar has implemented __getitem__ .)

Answer 2

The first parameter passed to the wrapper is an instance of the Run class, you should add self as the first parameter. Then you can refer to self.help_message and it will return the help_message defined in the Run class. Your example would become:

class foo(): 
    help_message = "" 
     
    def Help_Decorator(func): 
        def wrapper(self, data, context, caller): 
            try: 
                if data[0] == "help": 
                    return(self.help_message) #<--- cannot access this locally 
                else: 
                    return func(data,context,caller) 
            except: 
                return func(data,context,caller) 
        return wrapper 
  
class Bar(): 
    help_message = "A real help message!" 
    @foo.Help_Decorator 
    def Run(data,context,caller): 
        pass