The Eternal Squire wrote: > Suppose I have a central class with complex behavior that I want to > simply write as a bare skeleton upon which to hang the auxillary > classes that help provide the complex behavior.
So, it's akin to the GoF's Template Method or Strategy patterns, then. > What I will typically do is create the auxillary class as a friend so > that I can have tighter integration between the Skeleton instance and > an Auxillary member instance, where the Auxillary instance isolates > behavior that I might want to modify later through inheritance. > >class Auxillary (Friend): > def __str__ (self): > return "%s %d" % (self.__class__.__name__, self.friend.core_data) > >class Skeleton: > def __init__ (self): > self.auxillary = Auxillary (self) > >skeleton = Skeleton () > >print skeleton.auxillary This looks just like the Strategy pattern except that instead of storing the skeleton as a value within Auxiliary, you use a 'Friend' base class. I would argue that this obscures the code rather than makes it clearer. I would do this sort of thing in C++ where you need that base class to enforce the interface, but not in Python. I don't care what type I assign to self.auxillary as long as it supports the methods/properties I require, and it shouldn't care whether it's being assigned to a Skeleton or something else, as long as that object provides the data it requires. -- Ben Sizer -- http://mail.python.org/mailman/listinfo/python-list
