Question

I’m trying to get a local variable from a decorator. An example:

def needs_privilege(privilege, project=None):
    """Check whether the logged-in user is authorised based on the
    given privilege

    @type privilege: Privilege object, id, or str
    @param privilege: The requested privilege"""

    def validate(func, self, *args, **kwargs):
        """Validator of needs_privillige"""
        try: check(self.user, privilege, project)
        except AccessDenied:
            return abort(status_code=401)
        else: 
            return func(self, *args, **kwargs)

    return decorator(validate)

After decorating a function, like this:

 @needs_privilege("some_privilege")
 def some_function():
     pass

I would like to retrieve the ‘privilige’ variable (which validate() uses) from some_function. After searching more than one hour, I’m feeling pretty lost. Is this possible?

Edit:
Let me describe my problem a bit more thoroughly: can I get the string “some_prvilege” without executing some_function? Something like:

a = getattr(module, 'somefunction')
print a.decorator_arguments

? Thanks for helping me so far!

Answer 1

Your decorator basically check if a user have the permission to execute a given function, i don’t actually understand why you want to retrieve (to attach) the privilege to the function that was being wrapped but you can do this without adding another argument to all your functions.

def needs_privilege(privilege, project=None):
    """Check whether the logged-in user is authorised based on the
    given privilege

    @type privilege: Privilege object, id, or str
    @param privilege: The requested privilege"""

    def validate(func, self, *args, **kwargs):
        """Validator of needs_privillige"""
        try: check(self.user, privilege, project)
        except AccessDenied:
            return abort(status_code=401)
        else:
            return func(self, *args, **kwargs)
    validate.privelege = privelege
    return decorator(validate)

by the way your decorator should be like this :

def needs_privilege(privilege, project=None):
    def validate(func):
        def new_func(self, *args, **kwargs):
            try: 
                check(self.user, privilege, project)
            except AccessDenied:
                return abort(status_code=401)
            else:
                return func(self, *args, **kwargs)
        new_func.privilege = privilege
        return new_func
    return validate