Hi,

Here attached, a proposition of Camlp4 standard syntax extension for
macros. The file is named "pa_macro.ml". To compile it do:
      ocamlc -pp camlp4r -I +camlp4 -c pa_macro.ml

To use it for a file "foo.ml", do:
   To compile:
       ocamlc -pp "camlp4o ./pa_macro.cmo" foo.ml
   To just pretty print the resulting source:
       camlp4o ./pa_macro.cmo pr_o.cmo foo.ml

The added statements are indicated in the beginning of the file
pa_macro.ml.

Keywords uppercase or lowercase?

I choosed to write the keywords in uppercase because I consider that
they must be visible in the source, just like the "#define" and other
"#ifdef" of C are visible, because of the "#" and because of the fact
that they are in the first column.

And I have considered also that in an expression, it is important
to differentiate "ifs" as conditional compilation and normal "ifs".

On Thu, Oct 24, 2002 at 03:16:24PM +0200, Basile STARYNKEVITCH wrote:

>    #ifdef WANT_DEBUG
>    #define DEBUGME(V) if (debugflag) printf("%d", V)
>    #else
>    #define DEBUGME(V) {}
>    #endif

With pa_macro.cmo, you can write it like this:

   IFDEF WANT_DEBUG THEN
     DEFINE DEBUGME(v) = if (debugflag) then printf("%d", v)
   ELSE
     DEFINE DEBUGME(v) = ()
   END

To define "WANT_DEBUG" you can either insert in the source:
   DEFINE DEBUGME

Or add "-DWANT_DEBUG" as option:
   camlp4o ./pa_macros.cmo pr_o.cmo -DWANT_DEBUG foo.ml
   ocamlc -pp "camlp4o ./pa_macros.cmo -DWANT_DEBUG" foo.ml

> 5. having the equivalent of __FILE__ and __LINE__ is very useful

Ok file __FILE__.
For __LINE__, it is complicated. I added __LOCATION__.

Any comments?

-- 
Daniel de RAUGLAUDRE
http://cristal.inria.fr/~ddr/