How do you cast an instance to a derived class?

Question

I am trying to use a little inheritance in a Python program I am working on. I have a base class, User, which implements all of the functionality of a user. I am adding the co

Answer 1

• super(UnapprovedUser, self) is wrong it should be super(UnapprovedUser, cls) because in class method you do not have self available

• I will reiterate your question , in base class you are creating user and somehow you want to return derived class e.g.

   class User(object):

       @classmethod
       def get(cls, uid):
           return User()

   class UnapprovedUser(User):

       @classmethod
       def get(cls, uid):
           user = super(UnapprovedUser, cls).get(uid)
           return user # invalid syntax

   print UnapprovedUser.get("XXX")

it prints User object instead of UnapprovedUser object here you want UnapprovedUser.get to return UnapprovedUser, for that you can create a factory function which wil return appropriate user and than fill it with ldap

    class User(object):

        @classmethod
        def get(cls, uid):
            return cls.getMe()

        @classmethod
        def getMe(cls):
            return cls()

    class UnapprovedUser(User):

        @classmethod
        def get(cls, uid):
            user = super(UnapprovedUser, cls).get(uid)
            return user 

    print UnapprovedUser.get("XXX")

it prints UnapprovedUser object