Python 2.7如何从存储在不同类中的列表访问由一个类创建的对象

Question

I'm trying to create a class User that stores certain attributes about a user, and another class User_Review that has a list of the objects/instances created by class User.

class User(object):
    user_objects = []
    def __init__(self, name, age)
        self.name = name
        self.age = age
        User.user_objects.append(self)

class User_Review(User):
    user_list = # here is where I want user_objects to exist

user1 = User('leila', 23)
user2 = User('carter', 43)

# so user_list = [user1, user2]

To answer zondo and juanpa.arrivillaga, the purpose of User is to create objects with basic information, and User_Review is a method where I'd like to be able to do things with the list of users through other methods in the User_Review class, such as have methods that adds/removes users to the end of the user list, or display certain information (name only, for example).

Answer 1

For your purposes, I think you could instead of creating both the user_objects and user_list lists inside the classes, just retain the one inside User_Review (since you want their references to be stored in another class), and get rid of the one inside User , while simultaneously appending the created User object to the user_list from inside the __init__ method rather than user_objects .

In practice, this would look something like the following.

class User(object):
    def __init__(self, name, age):
        self.name = name
        self.age = age
        User_Review.user_list.append(self)

class User_Review(object):
    user_list = []

user1 = User('leila', 23)
user2 = User('carter', 43)

Printing out the name of the first user using print(User_Review.user_list[0].name) correctly outputs carter .

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This approach, however, seems fairly counter intuitive:

• The User_Review class inherits User which to me does not make any logical sense, since you would not want to have a method such as change_age in User_Review if it happened to be implemented in User . You would however, want to be able to access the data inside each User object, which can be accomplished by just accessing the required User inside the list.

• As it stands, User_Review serves no real purpose, exactly the same thing could be achieved by just a regular list; however, if there are plans for implementing methods that rely on data from multiple or all User objects created, then this might be a viable solution.

Other solutions to this problem could be creating the list inside the User class only, and just using User_Review to access that list and do the required actions. Or more complexly creating a separate class from these two dedicated to storing, organizing, and retrieving users to and from a database.