Re: [Caml-list] How to avoid compiling some code (like #ifdef in C)

[Markus Mottl <markus@oefai.at>]

On Wed, 10 Sep 2003, David MENTRE wrote:
> In my OCaml program, I want to make the _compilation_ (and not simply
> execution) of some part of the code optional (some internal auto-tests
> for example), depending on some configuration option.
> 
> In C, I would use an #ifdef for this.

In OCaml you can either also use the C-preprocessor or the preprocessor
camlp4, e.g. (using OCamlMakefile for specifying the preprocessor in
the topmost comment):

---------------------------------------------------------------------------
(*pp camlp4o pa_macro.cmo *)

open Printf

DEFINE Compile_code

let a () = printf "toto\n"

let _ =
  IFDEF Compile_code
  THEN
    let t = 1 in a ()
  ELSE
    ()
  END
---------------------------------------------------------------------------

Or as usual with cpp:

---------------------------------------------------------------------------
(*pp cpp *)

open Printf

#define Compile_code

let a () = printf "toto\n"

let _ =
  #ifdef Compile_code
    let t = 1 in a()
  #else
    ()
  #endif
---------------------------------------------------------------------------

Regards,
Markus Mottl

-- 
Markus Mottl          http://www.oefai.at/~markus          markus@oefai.at

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