From 8190746535320793676 X-Google-Thread: 7894ca11fe,ca1d48828e7eb066 X-Google-Attributes: gid7894ca11fe,public,usenet X-Google-NewGroupId: yes X-Google-Language: ENGLISH,ASCII-7-bit Path: g2news2.google.com!news2.google.com!npeer02.iad.highwinds-media.com!news.highwinds-media.com!feed-me.highwinds-media.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: Fri, 16 Oct 2009 09:40:17 -0500 Return-Path: To: (Usenet) From: Francis Glassborow Newsgroups: comp.std.c++ Subject: Re: Keyword abstract for pure virtual functions in c++0x Organization: unknown Sender: cppmods@cs.rpi.edu Approved: stephen.clamage@sun.com Message-ID: References: <64708d1f-cb87-4e3b-a1c8-845c98490c25@o41g2000yqb.googlegroups.com> <06f78e41-2741-4217-9d79-94bd729418d7@f20g2000prn.googlegroups.com> <1f008923-3930-4613-a4b9-1c575d97774a@k13g2000prh.googlegroups.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed X-Original-Date: Fri, 16 Oct 2009 13:03:25 +0100 X-Submission-Address: std-c++@netlab.cs.rpi.edu Date: Fri, 16 Oct 2009 09:31:06 CST Lines: 32 X-Usenet-Provider: http://www.giganews.com X-Trace: sv3-XLs+tbh1WfPDvmJ43p8vkWbLGTs2PSrZrc4/JrDPsKa9r+h/y8ipD2Al3xYYqSzJffXjlzQXiUa9w4z!JG6e4biMsDTb56s2+zRFcnn6xVaDDXII1Y7CiSARB0I8PCJCP3bqo0rLp3vd1EQ3+b5T 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 Xref: g2news2.google.com comp.std.c++:1496 Sean Hunt wrote: > On Oct 14, 12:37 pm, Francis Glassborow > wrote: >> Of course they notice because of the way that dtors chain together >> which is why you have to define your dtor even if you have declared it >> a pure virtual. > > Yes, but because the compiler defines a destructor for you if you > don't provide one, all classes inheriting from it will always provide > a replacement definition, so the pureness of a destructor won't affect > any inheritors. > > Sean Hunt > > No, the compiler only provides one if you have not declared it. As soon as you write: virtual ~mytype() = 0; you have declared it and the compiler is not at liberty to generate one for you (even though it would make some sense to allow that. Declaring any function as a pure virtual simply requires that the function is to be defined in derived classes it does not prevent definition within the base class. -- [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. If that fails, use mailto:std-c++@netlab.cs.rpi.edu] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://www.comeaucomputing.com/csc/faq.html ]