I’ve lost track of what you are arguing for here 😊 To bring the discussion back, here are my main points:
1. Scoped enums (enum class) for the sake of avoiding name clashes is useful for global enums, but when the enum lives inside a class, the chance that we’ll see a naming clash is minor, and using scoped enums in that case arguably has negative effects on code writability/readability. As a result, we should update the policy to not mandate scoped enums when the enum lives inside a class. 2. Scoped enums for the sake of type safety is a valid use case, but can be solved by promoting a warning to an error, and as such shouldn’t block us moving forward with #1. Cheers, Tor Arne > On 14 Aug 2018, at 15:00, Eike Ziller <eike.zil...@qt.io> wrote: > > > >> On 14. Aug 2018, at 13:18, Tor Arne Vestbø <tor.arne.ves...@qt.io> wrote: >> >> >>> On 14 Aug 2018, at 13:13, Eike Ziller <eike.zil...@qt.io> wrote: >>> >>> http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2347.pdf states >>> the problems that were the driver for creating strongly typed enums: >>> >>> 1. Implicit conversion to integer >>> 2. Inability to specify underlying type >> >> https://en.cppreference.com/w/cpp/language/enum describes types for unscoped >> enums too, curious, what’s the difference for the scoped enums? >> >>> 3. Scoping >>> >>>> that specifically mentions the enum inside a class use case a primary >>>> driver? >>> >>> Why would the implicit conversion problem be any different for enums inside >>> a class? >> >> It wouldn’t. I was referring to the scoping/name clash, which is what this >> discussion has been largely focusing on (so far). > > Now you cut off context. I was answering to: > >>>>> >>>>> There is one more very important aspect. Scoped enums can have dedicated >>>> types and are type safe. This could have easily caught issues like (which >>>> coincidently was pointed out to me this morning): >>>>> >>>>> https://codereview.qt-project.org/#/c/236736/ >>>>> >>>>> And I believe that is a very good reason to still prefer scoped enums. >>>> >>>> How frequent is this class of bugs? >>> >>> Frequent enough for it being the primary driver behind the introduction of >>> scoped enums?!? >> >> Do you have a source for this, that specifically mentions the enum inside a >> class use case a primary driver? > > Which is about type-safety, not scoping. > > -- > Eike Ziller > Principal Software Engineer > > The Qt Company GmbH > Rudower Chaussee 13 > D-12489 Berlin > eike.zil...@qt.io > http://qt.io > Geschäftsführer: Mika Pälsi, > Juha Varelius, Mika Harjuaho > Sitz der Gesellschaft: Berlin, Registergericht: Amtsgericht Charlottenburg, > HRB 144331 B _______________________________________________ Development mailing list Development@qt-project.org http://lists.qt-project.org/mailman/listinfo/development
