Re: New strongly type enum proposal featuring inherited enums

From:
Pete Becker <pete@versatilecoding.com>
Newsgroups:
comp.lang.c++.moderated,comp.std.c++,comp.lang.c++
Date:
Thu, 18 Aug 2011 07:51:59 CST
Message-ID:
<2011081706332351646-pete@versatilecodingcom>
On 2011-08-16 21:28:17 +0000, Phil Bouchard said:

Hi,

Is it too late to change the strongly type enum?


Yes, C++11 has been unanimously approved. It will be an official
standard in a few weeks.

No, work is just starting on the next version of the C++ standard.

 I have a proposal
that is much cleaner than what is on its way.

Right now we have:
enum class Val: unsigned long { E1, E2, E3, E4 };

Comments:
1) This design is bad because the ':' sign is reserved for inheritance.


Really? Where does the standard say that it's "reserved"? <g>

It's currently used to indicate inheritance, to separate two
expressions in a ternary operator, and to mark the size of a bitfield.

2) Inheriting from another enum would be quite useful. For example:
enum class Widget {button, combobox, listview};
enum class SuperWidget : Widget {iconview}

This way iconview would be equal to 3, not 0.


Sure. That's not precluded by using ':' to indicate that an enum is
based on an integral type.

--
 Pete
Roundhouse Consulting, Ltd. (www.versatilecoding.com) Author of "The
Standard C++ Library Extensions: a Tutorial and Reference
(www.petebecker.com/tr1book)

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