# Binding a method to a class

Python 2 draws a distinction between bound and unbound methods, whereas in Python 3 this distinction is gone: unbound methods have been removed from the language. To bind a method to a class compatibly across Python 3 and Python 2, you can use the `bind_method()` helper function:

    from future.utils import bind_method

    class Greeter(object):
        pass

    def greet(self, message):
        print(message)

    bind_method(Greeter, 'greet', greet)

    g = Greeter()
    g.greet('Hi!')

On Python 3, calling `bind_method(cls, name, func)` is equivalent to calling `setattr(cls, name, func)`. On Python 2 it is equivalent to:

    import types
    setattr(cls, name, types.MethodType(func, None, cls))