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Date: Tue, 18 Aug 2009 11:20:41 +0100
To: Edgar Friendly <thelema314@gmail.com>
Cc: caml-list@yquem.inria.fr
Subject: Re: [Caml-list] Conditional compilation
Message-ID: <20090818102041.GA4353@annexia.org>
References: <4A8A0B3C.10504@gmail.com>
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From: Richard Jones <rich@annexia.org>
X-Spam: no; 0.00; compilation:01 ifdef:01 foo:01 foo:01 autoconf:01 subst:01 makefile:01 ifdef:01 flags:01 flags:01 autoconf:01 ocaml:01 ocaml:01 2009:98 edgar:98 

On Mon, Aug 17, 2009 at 10:00:28PM -0400, Edgar Friendly wrote:
> Is there a better way to do this?  The path I'm following is looking
> very byzantine compared to C's [-DFOO] + [#ifdef FOO].

You can just use autoconf's ordinary features:

eg:

  AC_ARG_ENABLE([foo],
          [AS_HELP_STRING([--enable-foo],
            [enable foo @<:@default=no@:>@])],
          [],
          [enable_foo=no])
  
  # Define an automake conditional:
  AM_CONDITIONAL([FOO],[test "x$enable_foo" = "xyes"])
  
  # Define an autoconf substitution:
  if test "x$enable_foo" = "xyes"; then
    FOO=1
  else
    FOO=0
  fi
  AC_SUBST(FOO)

And then in Makefile.am you can use:

  ifdef FOO
  FLAGS = -DFOO=1
  else
  FLAGS =
  endif

and in any autoconf-substituted files you can use:

  @FOO@

We use autoconf/automake with OCaml code all the time, and it works
fine.  There are also OCaml macros available:

  http://forge.ocamlcore.org/projects/ocaml-autoconf/
  http://git.ocamlcore.org/cgi-bin/gitweb.cgi?p=ocaml-autoconf/ocaml-autoconf.git;a=summary

Rich.

-- 
Richard Jones
Red Hat