Thank you very much for the feedbacks. On Thu, Dec 20, 2018 at 4:52 AM Konstantin Tokarev <annu...@yandex.ru> wrote:
> > 19.12.2018, 12:53, "Fujii Hironori" <fujii.hiron...@gmail.com>: > > I'd like to change this because 'final' doesn't necessarily imply > > 'override'. See the following stackoverflow: > > https://stackoverflow.com/questions/29412412/does-final-imply-override > > It does imply override, unless it is used in a declaration of new virtual > method > (which has no practical meaning fwiw) > You are right. C++ allows using 'final' with 'virtual' without overriding. Even though I don't know practical use-cases for it, C++ allows it because 'final' doesn't mean overriding. And, this is the only reason 'final' doesn't necessarily imply override. This is a kind of chicken egg problem. I don't know which is true: 1. C++ allows it because 'final' doesn't mean overriding. 2. 'final' doesn't necessarily imply override because C++ allows it On Thu, Dec 20, 2018 at 6:28 AM Konstantin Tokarev <annu...@yandex.ru> wrote: > > > 19.12.2018, 23:27, "Michael Catanzaro" <mcatanz...@igalia.com>: > > On Wed, Dec 19, 2018 at 1:58 PM, Konstantin Tokarev <annu...@yandex.ru> > > wrote: > >> Adding override to method which already has final specifier doesn't > >> affect anything, > >> because both final and override may ony be used on virtual methods > > > > FWIW I prefer override because it's much more clear what that keyword > > is used for. > > If class itself has "final" specifier, "override" on methods works in the > same way > as "final", and I agree that it conveys intention more clear. I think so, especially after I will update the code style guidelines in Bug 192844. Bug 192844 – Update code style guidelines for using 'final' specifier for all classes which has no derived classes https://bugs.webkit.org/show_bug.cgi?id=192844 > However, Darin in [1] > suggested that we use "final" aggressively to avoid accidentally losing > compiler > optimization (i.e. devirtualization of call) > > [1] https://lists.webkit.org/pipermail/webkit-dev/2016-March/028022.html I think this won't be a problem after all classes which has no derived classes are capped with 'final'. On Thu, Dec 20, 2018 at 7:42 AM <ross.kirsl...@sony.com> wrote: > In that case, I'll point out that C++ Core Guidelines has a rule "Virtual > functions should specify exactly one of virtual, override, or final". > (http://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#Rh-override) > > Their tl;dr: > " > • virtual means exactly and only “this is a new virtual function.” > • override means exactly and only “this is a non-final overrider.” > • final means exactly and only “this is a final overrider.” > " > > FWIW, they also have a rule "Use final sparingly" with the note that > "Claims of performance improvements from final should be substantiated." > (http://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#Rh-final) > > C.128 is a same rule with the current WebKit coding style guidelines. But, I think C.128 makes sense with C.139. C.139 is against to Bug 192844. After Bug 192844 update, we will have a lot of 'final' classes, not sparignly.
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