What is the Python equivalent of a Ruby class method?

Question

In ruby you can do this:

class A
    def self.a
        'A.a'
    end
end

puts A.a #-> A.a

How can this be done in python. I need a method of a class to be called without it being called on an instance of the class. When I try to do this I get this error:

unbound method METHOD must be called with CLASS instance as first argument (got nothing instead)

This is what I tried:

class A
    def a():
       return 'A.a'

print A.a()

Answer 1

There are two ways to do this:

@staticmethod
def foo():     # No implicit parameter
    print 'foo'  


@classmethod
def foo(cls):   # Class as implicit paramter
    print cls

The difference is that a static method has no implicit parameters at all. A class method receives the class that it is called on in exactly the same way that a normal method receives the instance.

Which one you use depends on if you want the method to have access to the class or not.

Either one can be called without an instance.