> If you're building an extension tree, you'll either have to supply > layers of getter/setter methods, or hand-mangle references to attributes > defined in the superclass. > > Say you start with a "Point2D" class, and make the X, Y coordinates > double underscore. > > Now extend it to a "Point3D" class via inheritance. The 3D class > will not be able to access (set) the X, Y values without a setter method > defined in the parent OR by unmangling the parent names. > > If you'd used the common convention of single underscore as "don't > touch if you're an outsider", the 3D extension can be considered an > insider and directly access the X, Y > > Which would you rather read in a 3D point class derived by extending > a 2D point? > > def move(self, xmod, ymod, zmod): > self._z += zmod > self._y += ymod > self._x += xmod > > or > > def move(self, xmod, ymod, zmod): > super(Point3D, self).move(xmod, ymod) > self._z += zmod > > or > > def move(self, xmod, ymod, zmod): > self._Point2D__x += xmod > self._Point2D__y += ymod > self.__z += zmod > > Speaking for myself, I'd prefer the first > -- > Wulfraed Dennis Lee Bieber KD6MOG > wlfr...@ix.netcom.com wulfr...@bestiaria.com > HTTP://wlfraed.home.netcom.com/ > (Bestiaria Support Staff: web-a...@bestiaria.com) > HTTP://www.bestiaria.com/
I like the latter two styles, particularly the last one. That way you can see at a glance that those member variables are defined in the super class. But then I am a fan of Hungarian notation, which many programmers can't stand. -- http://mail.python.org/mailman/listinfo/python-list
