inject method into class

inject.py

from functools import wraps


def inject(klass):
    def decorator(func):
        @wraps(func)
        def wrapper(*args, **kwargs):
            return func(*args, **kwargs)

        setattr(klass, func.__name__, func)
        return wrapper

    return decorator


class Foo:
    pass


@inject(Foo)
def foo_hello(self):
    print('hello')


Foo().foo_hello()