Design pattern

pattern.md

From here

1. Decorateor

from functools import wraps

def makebold(fn):
    @wraps(fn)
    def wrapped():
        return "<b>" + fn() + "</b>"
    return wrapped

def makeitalic(fn):
    @wraps(fn)
    def wrapped():
        return "<i>" + fn() + "</i>"
    return wrapped

@makebold
@makeitalic
def hello():
    """a decorated hello world"""
    return "hello world"

print hello()

2. Adaptor

class Dog(object):
    def __init__(self):
        self.name = "Dog"

    def bark(self):
        return "woof!"


class Cat(object):
    def __init__(self):
        self.name = "Cat"

    def meow(self):
        return "meow!"


class Human(object):
    def __init__(self):
        self.name = "Human"

    def speak(self):
        return "'hello'"


class Car(object):
    def __init__(self):
        self.name = "Car"

    def make_noise(self, octane_level):
        return "vroom{0}".format("!" * octane_level)


class Adapter(object):
    def __init__(self, obj, **adapted_methods):
        """We set the adapted methods in the object's dict"""
        self.obj = obj
        self.__dict__.update(adapted_methods)

    def __getattr__(self, attr):
        """All non-adapted calls are passed to the object"""
        return getattr(self.obj, attr)


def main():
    objects = []
    dog = Dog()
    objects.append(Adapter(dog, make_noise=dog.bark))
    cat = Cat()
    objects.append(Adapter(cat, make_noise=cat.meow))
    human = Human()
    objects.append(Adapter(human, make_noise=human.speak))
    car = Car()
    objects.append(Adapter(car, make_noise=lambda: car.make_noise(3)))

    for obj in objects:
        print("A {0} goes {1}".format(obj.name, obj.make_noise()))


if __name__ == "__main__":
    main()