Guido Gonzato wrote:
| On Wed, 2 Jul 2003, I. Oppenheim wrote:
|
| > > m: ~n3 = n{o}n{m}n
|
| I think that m: is a wonderful and very useful extension to the standard,
| but AFAIK BarFly is the only program that supports it. In my view, macros
| shouldn't be part of the notation, and should be implemented using
| external tools like preprocessors. But that's just an opinion. I think
| I'll extend abcpp to add m: support.
|
| That said, if all developers are willing to implement m: in their
| programs, that't fine. Otherwise, abcpp will do the job for them.Macros are usually best handled by a separate pass that just expands them. One of the interesting things about the history of C is that there were a few compilers written that had the macros integrated into the language. This was generally considered a bad idea. In some cases, the macro code was stripped out, and replaced with a separate cpp pass. In the case of the C pre-processor, one of the interesting arguments was that the pre-processor is useful with a lot of other languages. If you look at C's macros, they really have little to do with C. About the only syntax that is really "C" is the /*...*/ comment; the rest is generic and works with most other languages. This was especially seen when the Berkeley folks came out with the compiler with multiple parsers, so the same compiler could handle C, Fortran and Pascal. New parsers could be (and were) written as plugins. The macro phase was done first, so C's macros could be used with all of the languages in the list. Perl has an option to run the code through cpp. So keeping C's macros in a separate program is a benefit to many other languages. It's not obvious that abc macros would be very useful to anything but abc. The above macro is pretty obviously musical, and of no obvious use anywhere else. But I wouldn't be too surprised if people found other uses for it. In any case, one of the vague and general lessons from the field of computing is that things that do text transformations like this are often more useful than you think at first. They are best done with standalone programs, so you can easily retarget them. You can invoke them by default (as C compilers do) or with an option (as perl does), but you probably don't want them integrated into your other programs. To subscribe/unsubscribe, point your browser to: http://www.tullochgorm.com/lists.html
