Path: csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!news.glorb.com!npeer01.iad.highwinds-media.com!news.highwinds-media.com!feed-me.highwinds-media.com!border3.nntp.dca.giganews.com!Xl.tags.giganews.com!border1.nntp.dca.giganews.com!nntp.giganews.com!local2.nntp.dca.giganews.com!news.giganews.com.POSTED!not-for-mail NNTP-Posting-Date: Sat, 31 Aug 2013 01:20:02 -0500 Return-Path: Sender: std-cpp-request@vandevoorde.com Approved: james.dennett@gmail.com Message-ID: <52204496.5050408@bawi.org> Newsgroups: comp.std.c++ From: Seungbeom Kim Subject: Is a union a kind of class? Organization: unknown Content-Type: text/plain; charset=us-ascii X-Original-Date: Fri, 30 Aug 2013 00:07:02 -0700 X-Submission-Address: std-cpp-submit@vandevoorde.com To: undisclosed-recipients:; Date: Sat, 31 Aug 2013 01:12:51 CST Lines: 23 X-Usenet-Provider: http://www.giganews.com X-Trace: sv3-k5Nytw4FNC/YTWljV7bHaYLr1ZdNTkw2uz5r0aKdgLB+iwWdypkNPjoCPC91Z+ykp/x+Ku6rr8UZMGz!bcC+upZ1oTeH3t/s6fukd+H79vWd3X7ZFph+kURAd6SZKfAZtA== X-Complaints-To: abuse@giganews.com X-DMCA-Notifications: http://www.giganews.com/info/dmca.html X-Abuse-and-DMCA-Info: Please be sure to forward a copy of ALL headers X-Abuse-and-DMCA-Info: Otherwise we will be unable to process your complaint properly X-Postfilter: 1.3.40 X-Original-Bytes: 2019 X-Received-Bytes: 2160 Xref: csiph.com comp.std.c++:651 In the taxonomy of C++ types, is a union a (kind of) class? 9[class]/5 clearly says, "A union is a class defined with the class-key union [...]". 5.1.2[expr.prim.lambda]/3 and 9[class]/10 also mention "a non-union class [type]", and 5.9[expr.rel]/2 "provided their class is not a union", all of which imply that a union is a class. On the other hand, 3.9.2[basic.compound]/1 lists classes and unions separately, which strongly implies that a union is not a class. If a union is a class, I think 3.9.2/1 is confusing (at best) and should be considered a defect. -- Seungbeom Kim [ comp.std.c++ is moderated. To submit articles, try posting with your ] [ newsreader. If that fails, use mailto:std-cpp-submit@vandevoorde.com ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://www.comeaucomputing.com/csc/faq.html ]