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Re: New strongly type enum proposal featuring inherited enums

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=?ISO-8859-15?Q?Daniel_Kr=FCgler?= <daniel.kruegler@googlemail.=
com> writes:
> >    enum class Widget : unsigned int { list_view, box, button };
> >    enum class SuperWidget : Widget { iconview };
>
> I don't know yet, what the meaning should be. For me one intuitive
> interpretation would be that SuperWidget has two enumerators of value 0.
> An alternative interpretation could be that SuperWidget::iconview has
> the numeric value 3 in this example.

Surely the latter...

That sort of usage seems very common in existing code, by doing
something like:

   enum X { a, b, X_MAX };
   enum Y { d = X_MAX + 1, e, Y_MAX };

Real inheritance seems like a natural way to sugar this up a bit.

Some other possible behavior:

* when the compiler does type checking of enum classes, consider enum
 classes related by inheritance compatible in some appropriate sense
 (e.g., an enum superclass can be assigned to an enum subclass, enum
 classes related by inheritance can be compared, etc)

* for enum classes, import all the members of the parent into the
 child, e.g.:

   enum class X : whatever { a, b };
   enum class Y : X { d, e };

 would yield X::a = 0, X::b = 1, Y::a = 0, Y::b = 1, Y::d = 2, Y::e = 3.

      [dunno about this one; maybe it's not desirable...]


-Miles

--
`...the Soviet Union was sliding in to an economic collapse so comprehensive
 that in the end its factories produced not goods but bads: finished products
 less valuable than the raw materials they were made from.'  [The Economist]


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New strongly type enum proposal featuring inherited enums Phil Bouchard <philippe@fornux.com> - 2011-08-16 21:28 -0600
  Re: New strongly type enum proposal featuring inherited enums Daniel Krügler <daniel.kruegler@googlemail.com> - 2011-08-18 07:54 -0600
    Re: New strongly type enum proposal featuring inherited enums Phil Bouchard<philippe@fornux.com> - 2011-08-24 14:06 -0700
      Re: New strongly type enum proposal featuring inherited enums Daniel Krügler<daniel.kruegler@googlemail.com> - 2011-08-24 17:39 -0700
        Re: New strongly type enum proposal featuring inherited enums Bart van Ingen Schenau<bart@ingen.ddns.info> - 2011-08-25 20:51 -0600
          Re: New strongly type enum proposal featuring inherited enums =3D?ISO-8859-15?Q?Daniel_Kr=3DFCgler?=3D <daniel.kruegler@googlemail.= com> - 2011-09-07 11:08 -0700
            Re: New strongly type enum proposal featuring inherited enums Miles Bader <miles@gnu.org> - 2011-09-08 14:46 -0700
              Re: New strongly type enum... why not use "using"? "peter miller"<fuchsia.groan@virgin.net> - 2011-09-12 11:18 -0700
                Re: New strongly type enum... why not use "using"? Miles Bader<miles@gnu.org> - 2011-09-13 09:29 -0700
                Re: New strongly type enum... why not use "using"? "peter miller"<fuchsia.groan@virgin.net> - 2011-09-15 14:13 -0700
  Re: New strongly type enum proposal featuring inherited enums Pete Becker <pete@versatilecoding.com> - 2011-08-18 07:51 -0600
    Re: New strongly type enum proposal featuring inherited enums Victor Bazarov<v.bazarov@comcast.invalid> - 2011-08-24 14:06 -0700
    Re: New strongly type enum proposal featuring inherited enums Paavo Helde<myfirstname@osa.pri.ee> - 2011-08-24 14:06 -0700
    Re: New strongly type enum proposal featuring inherited enums Francis Glassborow<francis.glassborow@btinternet.com> - 2011-08-24 14:52 -0700
      Re: New strongly type enum proposal featuring inherited enums Phil Bouchard<philippe@fornux.com> - 2011-08-24 17:39 -0700
  Re: New strongly type enum proposal featuring inherited enums Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2011-08-18 07:53 -0600
    Re: New strongly type enum proposal featuring inherited enums Phil Bouchard<philippe@fornux.com> - 2011-08-24 14:52 -0700
  Re: New strongly type enum proposal featuring inherited enums Marcel Müller <news.5.maazl@spamgourmet.com> - 2011-08-18 07:52 -0600
    Re: New strongly type enum proposal featuring inherited enums Phil Bouchard<philippe@fornux.com> - 2011-08-23 18:20 -0700
    Re: New strongly type enum proposal featuring inherited enums Phil Bouchard <philippe@fornux.com> - 2011-08-24 14:52 -0700
    Re: New strongly type enum proposal featuring inherited enums Phil Bouchard <philippe@fornux.com> - 2011-08-24 14:52 -0700
  Re: New strongly type enum proposal featuring inherited enums Francis Glassborow<francis.glassborow@btinternet.com> - 2011-08-24 14:06 -0700
  Re: New strongly type enum proposal featuring inherited enums "Bo Persson"<bop@gmb.dk> - 2011-08-24 14:06 -0700
  Re: New strongly type enum proposal featuring inherited enums red floyd<no.spam.here@its.invalid> - 2011-08-24 14:06 -0700
  Re: New strongly type enum proposal featuring inherited enums Seungbeom Kim<musiphil@bawi.org> - 2011-08-24 14:06 -0700
    Re: New strongly type enum proposal featuring inherited enums Phil Bouchard<philippe@fornux.com> - 2011-08-24 17:39 -0700
    Re: New strongly type enum proposal featuring inherited enums Phil Bouchard<philippe@fornux.com> - 2011-08-24 17:40 -0700
    Re: New strongly type enum proposal featuring inherited enums Phil Bouchard<philippe@fornux.com> - 2011-08-24 17:40 -0700

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