"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 usually skip the inheritance and make everything an instance of the > same class, e.g. > > class ASTNode(object): ... > > class Stmt(ASTNode): ... > class Expr(ASTNode): ... > class UnaryExpr(ASTNode): ... > class BinaryExpr(ASTNode): ... Eh? There's still inheritance here: Everything is derived from ASTNode. I understand that there is a separate design issue whether to make the hierarchy deep or shallow, but it's still a hierarchy. -- http://mail.python.org/mailman/listinfo/python-list
