From -6179507042981330438 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f78e5,765aa557d15ef5ba X-Google-Attributes: gidf78e5,public X-Google-Thread: fc772,a175c482da34ebf8 X-Google-Attributes: gidfc772,public X-Google-ArrivalTime: 2003-05-03 07:17:13 PST Path: archiver1.google.com!news1.google.com!newsfeed.stanford.edu!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!news1.optus.net.au!optus!news.mel.connect.com.au!news.unimelb.edu.au!bounce-back From: allan_w@my-dejanews.com (Allan W) Newsgroups: comp.std.c++,comp.lang.c++.moderated Subject: Re: Preprocessor evolution Date: 03 May 03 14:16:40 GMT Organization: http://groups.google.com/ Lines: 58 Approved: Fergus Henderson Message-ID: <7f2735a5.0305021101.16c15c25@posting.google.com> References: <652361f.0304032218.6b7a67e4@posting.google.com> <3e920e1f.883270640@News.CIS.DFN.DE> <3E94D1A2.5070406@ilog.com.sg> <3e9f0d33@andromeda.datanet.hu> <7f2735a5.0304241045.14708662@posting.google.com> <52f2f9cd.0305010835.b456aff@posting.google.com> NNTP-Posting-Host: taifun.cs.mu.oz.au X-Trace: ariel.ucs.unimelb.edu.au 1051971432 5881 128.250.34.72 (3 May 2003 14:17:12 GMT) X-Complaints-To: news@news.unimelb.edu.au NNTP-Posting-Date: 3 May 2003 14:17:12 GMT X-Original-Date: 3 May 2003 06:22:42 -0400 Delivered-To: std-c++@ucar.edu X-Submission-Address: c++-submit@netlab.cs.rpi.edu X-Auth: PGPMoose V1.1 PGP comp.lang.c++.moderated iQBVAwUAPrOYbkHMCo9UcraBAQGJKAH+L/zEwwuW+NfDyWd5Rx2+oczBKN41MwAv 4EUEe2yO46KNYJvS4DDdbzctDF+pwxZGprGHQFObEkPrlxhMoro/Bw== =LKLw X-Approved-For-Group: francis.moderator@robinton.demon.co.uk comp.lang.c++.moderated X-Scanned-By: MIMEDefang 2.28 X-Spam-Status: No, hits=-4.9 required=5.0 tests=NOSPAM_INC,REFERENCES,SPAM_PHRASE_00_01 version=2.41 X-Auth: PGPMoose V1.1 PGP comp.std.c++ Xref: archiver1.google.com comp.std.c++:19157 comp.lang.c++.moderated:65287 google@vandevoorde.com (Daveed Vandevoorde) wrote > I presented a set of language extensions I'm working > on at the recent ACCU conference (which, BTW, turned > out to be a very cool event). Somewhat unexpectedly, > it was also presented before a part of WG21/J16. > > I put up some notes at: > http://vandevoorde.com/Daveed/News/Archives/000015.html I found this hard to read -- not your writing style, but the HTML page. Your style sheet explicitly forces the body of the text to show up at 11-point font, overriding my browser's setting. On my screen, 11-point font is very difficult to read. I had to copy it into a word processor just to read it. The metacode concept itself seems interesting. I'm not sure that I would consider it a replacement for the preprocessor. We'll still need #include, #ifdef, and so on. Also, I wonder how many compilers are going to be able to implement all of this. It's quite extensive -- more so than some high-level languages. Would it be possible to implement metacode as a separate pre-compile step? If it has to run at the same time as the main translator, there could be difficulties (or at least performance issues) on platforms where the compiler is already considered a big program. I had some trouble understanding the second example in "Code Injection Primitives" -- the one where you inject field names. Is that supposed to generate float fieldfloat; int fieldint; char fieldchar; and so on for all known data types? Would that include pointers, pointers to pointers, pointers to pointers to pointers, ad nauseum? (If so, how would you end the infinite recursion?) Would it include user-defined classes? (If so, and you used it within the definition of a class -- would it include the class still being defined?) Will the code require knowledge of the internals of the current compiler -- how the symbol table is laid out, and so on? Will there be such a thing as "undefined behavior -- no diagnostic required" for metacode functions? Since they operate at compile time, it could easily cause the compiler itself to abort -- this would make debugging them somewhat difficult. I must say, I like this whole idea a lot better than some of the contortions being used to do the same things with templates. Especially things like is_lvalue and is_constant. I'm guessing that typeof() would be a predefined metacode function? [ Send an empty e-mail to c++-help@netlab.cs.rpi.edu for info ] [ about comp.lang.c++.moderated. First time posters: do this! ] [ 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. --- ]