#mix-in demo
 
class BaseObject(object):
    def __init__(self, *args, **kwargs):
        pass
       
 
class SolidObject(BaseObject):
    def __init__(self, *args, **kwargs):
        super(SolidObject, self).__init__(*args, **kwargs)
        # field declarations
 
        self.x = kwargs.get('x')
        self.y = kwargs.get('y')
        self.visibility = True

#mix-in 
class DestroyableObject(BaseObject):
    def __init__(self, *args, **kwargs):
        super(DestroyableObject, self).__init__(*args, **kwargs)
        self.obj_life = 100
 
    def hit(self):
        if self.obj_life > 0:
            self.obj_life -= 20
            print 'hit! life left: ' + str(self.obj_life)
        else:
            self.visibility = False
            print 'broken'
 

class Crate(SolidObject, DestroyableObject):
    def __init__(self, *args, **kwargs):
       super(Crate, self).__init__(*args, **kwargs)
       self.material = kwargs.get('material')
 
    def get_material(self):
        print self.material
 
 
wooden_crate = Crate(None, material='wood', x=0.1, y=-0.2)
cardboard_crate = Crate(None, material='cardboard', x=0.3, y=0.5)
 
for _ in range(6):
    wooden_crate.hit()
 
print wooden_crate.visibility
print cardboard_crate.visibility