Kurt Smith a écrit : > Hi List: > > Class inheritance noob here. > > For context, I have the following base class and subclass: > > class Base(object): > def __init__(self, val): > self.val = val > > class Derived1(Base): > def __init__(self, val): > super(Derived1, self).__init__(val) > > I'm curious as to other's thoughts on the following: when > incorporating optional behavior differences for a subclass, do you a) > make a new subclass (e.g., 'Derived2') and override (and add new) > methods that would encapsulate the new behavior, or b) keep the same > subclass around (i.e., 'Derived1'), but add an initialization option > that would specify the different behavior, and check for the value of > this option in the different methods?
You forgot the strategy pattern : extract the different behaviours into other objects (in Python, usually callback functions or custom callables) that are passed to the initializer and called when appropriate. This keeps a clean encapsulation of variations (ie you don't have to add new conditions and tests in your class) while avoiding class proliferation. Inheritance - while useful - is a bit oversold IMHO, specially in the context of a dynamic language. FWIW, inheritance is just a special case of composition/delegation... -- http://mail.python.org/mailman/listinfo/python-list
