From 8402581182139500211 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f78e5,ccb40040597f37a7 X-Google-Attributes: gidf78e5,public X-Google-ArrivalTime: 2003-03-08 21:26:46 PST Path: archiver1.google.com!news1.google.com!newsfeed.stanford.edu!logbridge.uoregon.edu!kibo.news.demon.net!mutlu.news.demon.net!demon!mail2news.demon.co.uk!devnull From: brangdon@cix.co.uk (Dave Harris) Newsgroups: comp.std.c++ Subject: Re: Extending enums (was Re: Forward declaration of enum) Date: Sun, 9 Mar 2003 05:26:38 +0000 (UTC) Lines: 45 Approved: fjh@cs.mu.oz.au (Fergus Henderson , moderator of comp.std.c++) Message-ID: References: X-Trace: mail2news.demon.co.uk 1047187599 5602 10.0.0.1 (9 Mar 2003 05:26:39 GMT) X-Complaints-To: abuse@demon.net NNTP-Posting-Date: Sun, 9 Mar 2003 05:26:39 +0000 (UTC) X-Received: from mulga.cs.mu.oz.au ([128.250.1.22]) by news.demon.co.uk with esmtp (Exim 4.05) id 18rtKW-0001SD-00 for mail2news@news.news.demon.net; Sun, 09 Mar 2003 05:26:37 +0000 X-Received: from localhost (localhost [[UNIX: localhost]]) by mulga.cs.mu.OZ.AU id QAA18413; Sun, 9 Mar 2003 16:26:32 +1100 (EST) X-Authentication-Warning: mulga.cs.mu.OZ.AU: fjh set sender to devnull@stump.algebra.com using -f X-Path: comp-std-cpp-robomod!not-for-mail X-Robomod: STUMP, ichudov@algebra.com (Igor Chudov) X-Delivered-To: std-c++@ncar.ucar.edu X-Newsgroups: comp.std.c++ X-Reply-To: brangdon@cix.co.uk X-Orig-NNTP-Posting-Host: pc1-clif1-6-cust113.nott.cable.ntl.com (80.4.200.113) X-Orig-X-Trace: fu-berlin.de 1047136326 65979472 80.4.200.113 (16 [57443]) X-MailScanner: PASSED (v1.2.7 17224 h28FC7mZ027282 mailbox5.ucsd.edu) X-Spam-Status: No, hits=-5.6 required=5.0 tests=QUOTED_EMAIL_TEXT,REFERENCES,SPAM_PHRASE_00_01 version=2.41 Xref: archiver1.google.com comp.std.c++:18233 kgwzamboni-news@zambonistiscan.com () wrote (abridged): > How about also making them more like real types. > > enum Color( Red, Orange, Yellow ); > enum Fruit( Orange, Apple, Grapes ); > > Except when assigning them directly to ints, the compiler is capable > of determining which Orange it is. It is a bit dangerous to have names whose meaning depends on context. > For that case allow the cast like Color(Orange). It's not really a cast; more of a name resolution. I think it is a shame enums do not have associated namespaces, so that we could write: enum Color { Red, Orange, Yellow }; enum Fruit { Orange, Apple, Grapes }; Colour c = Colour::Orange; Currently the second line is ambiguous even if Orange is not used subsequently, and the Colour::Orange syntax is not permitted. As a workaround I usually put my own namespace, like: namespace Color { enum Type { Red, Orange, Yellow }; } namespace Fruit { enum Type { Orange, Apple, Grapes } }; Colour::Type c = Colour::Orange; which works, but it is clumsy (eg there is no good name for the thing I have called "Type"). Dave Harris, Nottingham, UK | "Weave a circle round him thrice, brangdon@cix.co.uk | And close your eyes with holy dread, | For he on honey dew hath fed http://www.bhresearch.co.uk/ | And drunk the milk of Paradise." --- [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. If that fails, use mailto:std-c++@ncar.ucar.edu ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://www.jamesd.demon.co.uk/csc/faq.html ]