Decorator Pattern vs. Multiple Inheritance.

decovsmuli.py

#!/usr/bin/python2

class Window(object):
    def draw(self, device):
        device.append('flat window')
    def info(self):
        pass

# The subclass approch
class BorderedWindow(Window):
    def draw(self, device):
        super(BorderedWindow, self).draw(device)
        device.append('borders')

class ScrolledWindow(Window):
    def draw(self, device):
        super(ScrolledWindow, self).draw(device)
        device.append('scroll bars')

# Here is the important point of this approch
class MyWindow(ScrolledWindow, BorderedWindow, Window):
    pass

def test_muli():
    w = MyWindow()
    dev = []
    w.draw(dev)
    print dev
def test_muli2():
    MyWindow = type('MyWindow', (ScrolledWindow, BorderedWindow, Window), {})
    w = MyWindow()
    dev = []
    w.draw(dev)
    print dev

# The decorator approch
class WindowDecorator:
    def __init__(self, w):
        self.window = w
    def draw(self, device):
        self.window.draw(device)
    def info(self):
        self.window.info()

class BorderDecorator(WindowDecorator):
    def draw(self, device):
        self.window.draw(device)
        device.append('borders')

class ScrollDecorator(WindowDecorator):
    def draw(self, device):
        self.window.draw(device)
        device.append('scroll bars')

def test_deco():
# Here is the important point of this approch
    w = ScrollDecorator(BorderDecorator(Window()))
    dev = []
    w.draw(dev)
    print dev

test_muli()
test_muli2()
test_deco()