Andrew Koenig wrote: > "Lonnie Princehouse" <[EMAIL PROTECTED]> wrote in message > news:[EMAIL PROTECTED] > > >>If you try this sort of inheritance, I'd recommend writing down the >>formal grammar before you start writing classes. Don't try to define >>the grammar through the inheritance hierarchy; it's too easy to >>accidentally build a hierarchy that can't be translated into a >>single-pass-parsable grammar... > > > Understood. I was using expression trees as a contrived example, and really > want to know about the Python community's stylistic preferences for defing > such hierarchies that don't absolutely need a root.
I have used empty or near-empty base classes to be some sort of class 'tag' for the derived classes. Much like Java's Serializable interface; it adds nothing on a functional level but you can check if a class has a 'tag' by checking if it is an instance of the base class. I don't know if this is good style in Python but I tend to use it sometimes (probably because I do Java at work ;-) --Irmen -- http://mail.python.org/mailman/listinfo/python-list
