DCI in python: Adding and deleting methods from objects.

gistfile1.py

def add_role(subject, role):
    for name, function in inspect.getmembers(role, predicate=inspect.isfunction):
            setattr(subject, name, types.MethodType(function, subject))

def remove_role(subject, role):
    for name, function in inspect.getmembers(role, predicate=inspect.isfunction):
            delattr(subject, name)
            
class Person:
    pass

class Greeter:
    def greet(self):
        print("Hi")
        

p = Person()
add_role(p, Greeter)
p.greet()
remove_role(p, Greeter)
p.greet()

#>>> p = Person()
#>>> add_role(p, Greeter)
#>>> p.greet()
#Hi
#>>> remove_role(p, Greeter)
#>>> p.greet()
#Traceback (most recent call last):
#  File "<stdin>", line 1, in <module>
#AttributeError: 'Person' object has no attribute 'greet'