From 6910685961382097778 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 109fba,109af18a94b8a35c X-Google-Attributes: gid109fba,public X-Google-Thread: f78e5,e5cae9ffbf1dd57e,start X-Google-Attributes: gidf78e5,public X-Google-ArrivalTime: 1992-10-02 14:29:06 PST Xref: sparky comp.lang.c++:14452 comp.std.c++:1285 Newsgroups: comp.lang.c++,comp.std.c++ Path: sparky!uunet!munnari.oz.au!metro!extro.ucc.su.OZ.AU!maxtal From: maxtal@extro.ucc.su.OZ.AU (John MAX Skaller) Subject: Re: The concept of templates considered ill designed Message-ID: <1992Oct2.153826.12051@ucc.su.OZ.AU> Sender: news@ucc.su.OZ.AU Nntp-Posting-Host: extro.ucc.su.oz.au Organization: MAXTAL P/L C/- University Computing Centre, Sydney References: <1992Oct1.140643.9775@cadsun.corp.mot.com> Date: Fri, 2 Oct 1992 15:38:26 GMT Lines: 56 In article <1992Oct1.140643.9775@cadsun.corp.mot.com> shang@corp.mot.com writes: > >Thank you, Raymond, for raising this thread. I'd like to fork it >to comp.std.c++ for standard committee to reconsider whether template should be >accepted as C++ standard. How would you modify the template idea to be better? > >In article stefans@bauv106.bauv.unibw-muenchen.de >(Stefan Schwarz) writes: > >> Would be interesting to hear from library-developers about shipping their >> products together with source-code. > >Right to the point. Would be interesting also to hear about from the >library-users about reading the source code to detect where are the source of >the usage error. > >Template is not a self-enclosed type-safe language feature, i.e. it cannot be >compiled separately to ensure type-error free. All type errors about the class >parameters are checked when the template is used. When the library-developers >ship their products, they cannot ensure their templates are type-error free. This is not true, of course they can. What you mean is that the compiler doesn't help very much, and I agree. But I'm sure one could prove that a template was error free by hand ( I agree this is not formal system like a compiler check, but lets not get into whether a proof actually proves what it purports to or not: the usual solution to this problem is to publish the proof ). >The library user will get confused when an error is reported on the source code >of the template: "should it be my fault or the fault of the template itself?" > >In sense of the relationship between developer and user, template is something >like untyped function (I don't refer to run-time type error). > >David Shang I agree but am too stupid to see how the situation could be improved. For a template class C, it will be the case that C makes sense C is illegal depending on T1 and T2. One cant check that until use, unless perhaps you have to predeclare: class C; // causes expansion NOW! -- ;---------------------------------------------------------------------- JOHN (MAX) SKALLER, maxtal@extro.ucc.su.oz.au Maxtal Pty Ltd, 6 MacKay St ASHFIELD, NSW 2131, AUSTRALIA ;--------------- SCIENTIFIC AND ENGINEERING SOFTWARE ------------------