Excerpts from Yuri Shtil's message of Thu Sep 03 19:08:17 -0400 2009: > What is wrong in excluding some of the derived classes from a subtype > definition?
Like Chris said: > > One of the main points to object orientation is Subtype Polymorphism > > ... meaning derived classes can be substituted for main classes, why > > would you want to throw that away? So, it breaks a fundamental part of OO. That's what's wrong with it. > It has nothing to do with inheritance/Polymorphism. I just want to limit > what can be saved in the attribute. "Officer, I'm not driving under the influence, I just had a few beers and now I'm operating this vehicle." Subclasses that have less functionality than their superclasses are almost always a design smell. Maybe part of your superclass should actually be a role? I'm sure that if you wanted to give more specifics, people would be willing to help look for a solution to your problem that is less likely to bite you later. hdp.
