On Friday, May 1, 2015 at 12:03:35 PM UTC+1, Aryeh Gregor wrote: > On Thu, Apr 30, 2015 at 6:49 PM, Trevor Saunders wrote: > > I don't think it would actually be backward incompatible the only > > changes would be turning invalid programs into valid ones. > > Given that "void foo() override;" currently makes foo() a virtual > function, allowing override on non-virtual functions would have to > change the meaning to make foo() non-virtual.
Not exactly, afaict, since it would also produce an error in any case where foo wasn't *already* implicitly a virtual. So adding override can only add additional information in the case where it causes an error. And since nobody cares (from a general pov) about turning invalid programs into valid ones, it could theoretically be changed in a future C++ version. That said, it won't happen, since the entire purpose of override is to allow programmers to explicitly confirm that they are overriding a virtual method from a superclass, so allowing override for a method that doesn't override a virtual is completely nonsensical. If it was valid for methods that didn't override, it would act exactly the same as virtual, so would serve no purpose, unless it counted as "virtual only if overriding a virtual, otherwise non-virtual", in which case it would be identical to the implicit behavior, except it would cause huge confusion if applied to a non-overriding method. So you can probably trust that will never happen. As for final, final attempts to prevent any subclasses from overriding a virtual method. You can't override a non-virtual, so final on a non-virtual would serve no purpose (except perhaps to prevent all subclasses from reusing a method name and hiding the superclasses method? but that seems like something that should be avoided regardless and is better solved with a compiler-warning than a language feature...). _______________________________________________ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
