> I mean that different classes respond to the same message in a
> different albeit appropriate fashion.
ah, well, that is very different from your original statement.
> >> Admittedly Tk does poorly here, but it does have re-use, mostly
> >> because common stuff is split off into utility functions. No, Tk
> >> doesn't support _further_ inheritance without re-organising the code,
> >> but the re-use is there through splitting off common stuff.
> >that isn't inheritance, it's reuse.
> Implementation inheritance is just a formalised discipline for code
> re-use. Take a look at a language which separates the concepts of
> interface and implementation inheritance.
i use one. objective-c, the unsung contributor to java.
> >> So Tk is a good example of how not to do OO. How much cleaner it would
> >> be if it did OO properly.
> >> Now look at Stk. They have put a layer on top making Tk appear to
> >> fully support inheritance, and you can inherit and make
> >> specialisations of widgets and everything. Infinitely more powerful
> >> than Tcl/Tk can ever be.
> >or you could just start with a language that does it right from the start.
> Stk Scheme is a language which _has_ "done it right" from the start.
i don't know that Tk is a good thing to use, but point taken.