Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!sun-barr!cs.utexas.edu!sdd.hp.com!usc!snorkelwacker.mit.edu!bloom-beacon!eru!hagbard!sunic!news.funet.fi!funic!fuug!mjolner!newshost!eru From: eru@tnvsu1.tele.nokia.fi (Erkki Ruohtula) Newsgroups: comp.std.c Subject: Order to pragma chaos (was Re: Another sizeof question) Message-ID: Date: 23 Nov 90 12:50:07 GMT References: <13171@crdgw1.crd.ge.com> <12570055@hpclscu.HP.COM> Sender: news@mjolner.tele.nokia.fi Distribution: comp Organization: Nokia Telecommunications Lines: 34 In-reply-to: shankar@hpclscu.HP.COM's message of 20 Nov 90 01:43:03 GMT In article <12570055@hpclscu.HP.COM> shankar@hpclscu.HP.COM (Shankar Unni) writes: Thus the only reasonable approach is to say that a "#pragma" can change the behavior of a program in really unspecified ways (unless you want to get into the business of standardizing specific pragmas, like Ada does). I think that to some extent, this might be a good idea. The problem with pragmas is that although many compilers have similar special features, the ways to invoke them differ. Disabling structure alignment is a good example. One compiler I know expects "#pragma noalign", another "#pragma pack". There could be a clearing-house where implementors could send questions like "I want to add a special feature X. What kind of a pragma (if any) has been used for it before? if none, I intend to use #pragma ZZZ". The clearing-house would send back either a suggestion about an existing pragma, or tell the implementor to go ahead with his own idea (and archive it for later queries). It would have the process these queries fairly quickly to be useful, but this is possible if we stick to the idea that the implementors suggestions for new pragmas are accepted without worldwide discussion. Implementors would also be asked to report if they improve the pragma they got (for example, in the pack case, adding an optional number to specify that data must be aligned to offsets divisible by that number should be reported). The collected pragmas would be viewed as recommendations, not part of the standard. I believe this kind of arrangement could reduce unnecessary incompatibility in the areas that fall outside the scope of the standard. -- Erkki Ruohtula / Nokia Telecommunications eru@tele.nokia.fi / P.O. Box 33 SF-02601 Espoo, Finland Disclaimer: These are my private opinions and do not represent the position of Nokia Telecommunications.