From 6867213877607416588 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f78e5,7b79e159eaf7fc79,start X-Google-Attributes: gidf78e5,public Path: g2news1.google.com!news1.google.com!news.glorb.com!peer1.news.newnet.co.uk!peer1.news.newnet.co.uk!kibo.news.demon.net!mutlu.news.demon.net!demon!mail2news.demon.co.uk!devnull From: usenet@disemia.com (edA-qa mort-ora-y) Newsgroups: comp.std.c++ Subject: Template visibility / linkage Date: Tue, 22 Jun 2004 17:53:30 +0000 (UTC) Organization: Arcor Lines: 71 Approved: fjh@cs.mu.oz.au (Fergus Henderson , moderator of comp.std.c++) Message-ID: <40d85d55$0$25274$9b4e6d93@newsread2.arcor-online.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-Trace: mail2news.demon.co.uk 1087926810 22987 10.0.0.1 (22 Jun 2004 17:53:30 GMT) X-Complaints-To: abuse@demon.net NNTP-Posting-Date: Tue, 22 Jun 2004 17:53:30 +0000 (UTC) X-Received: from mulga.cs.mu.oz.au ([128.250.1.22]) by news.demon.co.uk with esmtp (Exim 4.12) id 1BcpSb-0005yb-00 for mail2news@news.news.demon.net; Tue, 22 Jun 2004 17:53:30 +0000 X-Received: from mulga.cs.mu.OZ.AU (localhost [127.0.0.1]) by mulga.cs.mu.OZ.AU with ESMTP id i5MHrRRR002940; Wed, 23 Jun 2004 03:53:27 +1000 (EST) X-Received: (from fjh@localhost) by mulga.cs.mu.OZ.AU (8.12.10+Sun/8.12.9/Submit) id i5MHrQVB002930; Wed, 23 Jun 2004 03:53:26 +1000 (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++@ucar.edu X-User-Agent: Mozilla Thunderbird 0.6 (X11/20040502) X-Accept-Language: en-us, en X-Newsgroups: comp.std.c++ X-NNTP-Posting-Date: 22 Jun 2004 18:24:53 MEST X-Spam-Checker-Version: SpamAssassin 2.60-mulga_r1 (1.212-2003-09-23-exp) on mulga.cs.mu.OZ.AU X-Spam-Level: X-Spam-Status: No, hits=-4.9 required=5.2 tests=BAYES_00 autolearn=ham version=2.60-mulga_r1 Xref: g2news1.google.com comp.std.c++:983 I am having difficulty determining what the proper linkage/locating of templates and their specializations (Section 3.5.4 briefly mentions template linkage, and 14 talks about the export keyword). Situation A: In : template void func( T val ); In : #include "header1" template<> void func( int val ) { ... } In : #include "header1" .. int a; func( a ); Comments: In this situation, should the code in end up calling the template specialization as defined in , even though it is unaware of its existence at compile time? Since the linkage of the template is external, and it has the same signature, I would assume yes. Situation B: In : template void func( T val ) { /* primary def */ } In : #include "header1" template<> void func( int val ) ... In : #include "header1" .. int a; func( a ); Comments: Should the code in use the primary template definition or should it use the specialization from ? My reading of the standard indicates it should use the specializaed form, since the template matching doesn't appear to be limited to the current translation unit, and the the function signature will match that in at link time. I am unclear of whether the template matching rules hold over to link time, or only for the current translation unit. That is, if , in both cases, were to also include it would be clear that it usese the specialization, but since it doesn't include , the compilation finishes without knowledge of the specialization. Does the linker then /do the right thing/? And I'm completely unclear on classes, whether they should match identical declarations in other units, as there would be signifcant sizing problems for the compiler. Though I can't see why it would be disallowed according to the standard. -- edA-qa mort-ora-y (Producer) Trostlos Records "What suffering would man know if not for his own?" --- [ 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 ]