Guido van Rossum wrote:
On Sat, Mar 28, 2009 at 7:40 PM, Nick Coghlan <ncoghlan@gmail.com> wrote:
Agreed - the base class author has no right to tell subclass authors that they *can't* do something.
I'm sorry, but this is going too far. There are plenty of situations where, indeed, this ought to be only a hint, but I think it goes to far to say that a base class can never have the last word about something.
Sorry, what I wrote was broader in scope than what I actually meant. I only intended to refer to otherwise arbitrary non-functional constraints like marking elements of the base as "private" or "final" without giving a subclass author a way to override them (after all, even name mangling can be reversed with sufficient motivation). A base class obviously needs to impose some real constraints on subclasses in practice, or it isn't going to be a very useful (if nothing else, it needs to set down the details of the shared API). Cheers, Nick. -- Nick Coghlan | ncoghlan@gmail.com | Brisbane, Australia ---------------------------------------------------------------