Python Programming

Like class attributes, you can also have class methods that are bound to the class (and not to the class instance).

A class method takes the class (cls) as its first argument, rather than the class instance (self) as in an instance method.

Thus, class methods do not have access to the object instance (via self), but only the class (via cls). Therefore, it does not have access to any instance attributes or methods.

Writing a class method is just like writing an instance method, except that you define cls instead of self as the first argument (PEP 8 recommends this convention). You will also need to annotate the method with a @classmethod decorator (Line 9). This decorator allows Python to know that cls is a class, and not an instance!

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class Person:
    count = 0

    def __init__(self, name, age):
        self.name = name
        self.age = age
        Person.count += 1

    @classmethod
    def get_population(cls):
        return f"Population: {cls.count}"

lecturer = Person("Josiah", 20)
print(Person.get_population())
print(lecturer.get_population())