@classmethod vs @staticmethod vs "plain" methods
# @classmethod vs @staticmethod vs "plain" methods
# What's the difference?
class MyClass:
def method(self):
"""
Instance methods need a class instance and
can access the instance through `self`.
"""
return 'instance method called', self
@classmethod
def classmethod(cls):
"""
Class methods don't need a class instance.
They can't access the instance (self) but
they have access to the class itself via `cls`.
"""
return 'class method called', cls
@staticmethod
def staticmethod():
"""
Static methods don't have access to `cls` or `self`.
They work like regular functions but belong to
the class's namespace.
"""
return 'static method called'
# All methods types can be
# called on a class instance:
>>> obj = MyClass()
>>> obj.method()
('instance method called', <MyClass instance at 0x1019381b8>)
>>> obj.classmethod()
('class method called', <class MyClass at 0x101a2f4c8>)
>>> obj.staticmethod()
'static method called'
# Calling instance methods fails
# if we only have the class object:
>>> MyClass.classmethod()
('class method called', <class MyClass at 0x101a2f4c8>)
>>> MyClass.staticmethod()
'static method called'
>>> MyClass.method()
TypeError:
"unbound method method() must be called with MyClass "
"instance as first argument (got nothing instead)"