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Date: Thu, 28 Aug 2003 17:09:19 +0100
To: caml-list@inria.fr
Subject: [Caml-list] I need a C preprocessor
Message-ID: <20030828160919.GA8257@redhat.com>
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From: Richard Jones <rich@annexia.org>
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X-Spam: no; 0.00; compile-time:01 submenu:99 accel:01 submenu:99 accel:01 freshmeat:01 ltd:98 ifdef:01 ifdef:01 debug:01 debug:01 ocaml:01 dump:01 dump:01 simpler:01 
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Here is some code I've just written. CjsConfig.debug_menu is a
compile-time constant.

  let debug_menu =
    if CjsConfig.debug_menu then
      Some (factory#add_submenu "Debug")
    else
      None in

  (* ... *)

  let single_step_ev_item, single_step_res_item, step_to_item,
      dump_hiertext_item =
    match debug_menu with
      None -> None, None, None, None
    | Some debug_menu ->
	let factory = new GMenu.factory debug_menu ~accel_group in
	let single_step_ev_item =
	  factory#add_item "Single Step (1 Event)"
	    ~key:GdkKeysyms._T in
	let single_step_res_item =
	  factory#add_item "Single Step (1 Result Period)"
	    ~key:GdkKeysyms._Z in
	let step_to_item = factory#add_item "Step To ..." in
	factory#add_separator ();
	let dump_hiertext_item =
	  factory#add_item "Dump HierText To Console"
	    ~key:GdkKeysyms._H in
	(Some single_step_ev_item, Some single_step_res_item,
	 Some step_to_item, Some dump_hiertext_item)
  in

Now in C I'd use the preprocessor:

#ifdef DEBUG_MENU
  factory#add_submenu "Debug"
#endif

#ifdef DEBUG_MENU
  let factory = new GMenu.factory debug_menu ~accel_group in
  let single_step_ev_item = factory#add_item "Single Step (1 Event)"
  (* etc. *)
#endif

which results in briefer, faster and simpler to understand code.

My question is what is the proper style for this sort of thing in
OCaml?

Rich.

-- 
Richard Jones. http://www.annexia.org/ http://freshmeat.net/users/rwmj
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