Using class method to access class variable within a class

Question

I have a question regarding accessing class variable from the class. Which way is preferred? Why Version 1 works? name isn't instance variable, how it can be accessed using .self?

Version 1:

class Base:
    def get_name(self): return self.name

class Child_1(Base):
    name = 'Child 1 name'

child = Child_1()
print(child.get_name())

Version 2:

class Base:
    @classmethod
    def get_name(cls): return cls.name

class Child_1(Base):
    name = 'Child 1 name'

child = Child_1()
print(child.get_name())

Motivation behind this, is defining name once for all instances to save space.

Version 1 will not always get the class attribute. If there is an instance attribute name it will return that. — Klaus D.
– Klaus D., Commented May 14, 2020 at 7:56
stackoverflow.com/a/25577642/6045800 TL;DR - Well, accessing a class attribute through self works just fine. If there is no instance attribute of the same name, you get the class attribute. But assigning to it will hide the class attribute with a new instance attribute of the same name. Which is probably not what you wanted. — Tomerikoo
– Tomerikoo, Commented May 14, 2020 at 7:57
Version 1 is typically preferred unless you have a very good reason not to (ie provide more protection against accidentally setting it) — Joran Beasley
– Joran Beasley, Commented May 14, 2020 at 7:58

Joran Beasley · Accepted Answer · 2020-05-14 07:56:17Z

1

self.name by default refers to cls.name

if you set it it only sets it for that instance however

self.name = "bob"

now overrides the class level name

just the same for methods as well

class Foo:
    @staticmethod
    def hello():
        print("Hi There From Foo!")
    def __init__(self):
        self.hello() #this works

 Foo.hello() # this also works
 Foo() # print from in the init

answered May 14, 2020 at 7:56

Joran Beasley

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