From 3872258431923591064 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f78e5,c45bddfadd5b4855 X-Google-Attributes: gidf78e5,public X-Google-ArrivalTime: 1994-09-14 00:23:18 PST Path: bga.com!news.sprintlink.net!sundog.tiac.net!usenet.elf.com!news2.near.net!MathWorks.Com!yeshua.marcam.com!charnel.ecst.csuchico.edu!olivea!koriel!male.EBay.Sun.COM!engnews1.Eng.Sun.COM!engnews2.Eng.Sun.COM!usenet From: clamage@Eng.Sun.COM (Steve Clamage) Newsgroups: comp.std.c++ Subject: Re: C++ templates standard Date: 13 Sep 1994 21:49:38 GMT Organization: Sun Microcomputer Corporation Lines: 34 Message-ID: <3556pi$290@engnews2.Eng.Sun.COM> References: Reply-To: clamage@Eng.Sun.COM NNTP-Posting-Host: taumet.eng.sun.com In article 1yu@hpgndlab.grenoble.hp.com, jr@grenoble.hp.com (Jean-Rene Bouvier) writes: >In article , jason@cygnus.com (Jason Merrill) writes: >> >>>>> Jean-Rene Bouvier writes: >> >> > I've tried several compilers for the following piece of code, but none >> > accepted it. >> > Does anyone know whether my code is legal or not ? >> >> It isn't. Class templates cannot be nested. >> >> Jason > >Is there any reason - besides compilers complexity - to forbid nested >templates. I can't see why there would be an issue with them, has that >question been debated at ANSI ? This is explained in detail in "The Design and Evolution of C++". When the template feature was being designed, no one knew what all the consequences would be of nested templates, and there were no actual implementations of templates at the time the ARM was written. Rather than allow something that might later have to be removed from the language, Stroustrup made the rule that templates may appear only at file scope. Later experience has showed that there are indeed some problems, particularly with allowing template virtual functions, but that for most cases the rule about file scope can be relaxed. The C++ Committee has approved a relaxed rule. Few, if any, compilers allow nested templates yet because the feature is too new. --- Steve Clamage, stephen.clamage@eng.sun.com