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

What you’re looking for is the staticmethod decorator, which can be used to make methods that don’t require a first implicit argument. It can be used like this:

class A(object):
    @staticmethod
    def a():
        return 'A.a'

On the other hand, if you wish to access the class (not the instance) from the method, you can use the classmethod decorator, which is used mostly the same way:

class A(object):
    @classmethod
    def a(cls):
        return '%s.a' % cls.__name__

Which can still be called without instanciating the object (A.a()).