From -7165891974056025068 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f78e5,aef96954609d602c X-Google-Attributes: gidf78e5,public X-Google-ArrivalTime: 1993-08-16 10:36:55 PST Newsgroups: comp.std.c++ Path: gmd.de!xlink.net!howland.reston.ans.net!usc!elroy.jpl.nasa.gov!decwrl!netcomsv!netcom.com!rfg From: rfg@netcom.com (Ronald F. Guilmette) Subject: Re: Template constraints Message-ID: Organization: Netcom Online Communications Services (408-241-9760 login: guest) References: <1993Aug16.004133.23916@mole-end.matawan.nj.us> Date: Mon, 16 Aug 1993 17:08:22 GMT Lines: 42 In article <1993Aug16.004133.23916@mole-end.matawan.nj.us> mat@mole-end.matawan.nj.us writes: >In article , rfg@netcom.com (Ronald F. Guilmette) writes: > >> Regarding the problem of syntax checking of templates... > ... >> (It is a fairly well known fact that it is often hard, if not impossible to >> produce link-time diagnostics which point the user back to the original >> source file and original source line which is really causing the problem. >> Therefore, if given the choice, I would always opt for a language design >> which makes it possible to generate a maximal number of the required >> diagnostics at compile-time rather than putting everything off until link- >> time.) > >Ron, I hope you'll forgive me if I tread this ground again; I know we've >done it elsewhere. > >The `compile-then-link' model assumes that all semantic analysis (and code >generation) can be performed before any name resolution (or relocation). >Templates break this assumption, since semantic analysis must be deferred >until the template is specialized, and the template can't be specialized >until the entire program is present (because specialization depends on what >has been written `manually'). > >Thus the notions of `compile time' and `link time' get rather badly blurred. While I would agree that templates do indeed have such a "blurring" effect, they most certainly DO NOT (and cannot) eliminate the important distinction between "compile-time" and "link-time" as far as the C++ standard is concerned. There will ALWAYS be errors which MUST be diagnosed at "compile-time", and, similarly, there will always be certain kinds of errors which MUST be diagnosed at "link-time". To the extent that diagnostics for template-related (erroneous) usage is NOT explicitly mandated to occur at one or the other of these two times, the specification (in the C++ standard) of the templates feature is incom- plete. -- -- Ronald F. Guilmette ------------------------------------------------------ ------ domain address: rfg@netcom.com --------------------------------------- ------ uucp address: ...!uunet!netcom.com!rfg -------------------------------