(*
* Global - Mutable global variable
* Copyright (C) 2003 Nicolas Cannasse
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version,
* with the special exception on linking described in file LICENSE.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*)
(** Mutable global variable.
Often in OCaml you want to have a global variable, which is mutable
and uninitialized when declared. You can use a ['a option ref] but
this is not very convenient. The Global module provides functions
to easily create and manipulate such variables.
*)
type 'a t
(** Abstract type of a global *)
exception Global_not_initialized of string
(** Raised when a global variable is accessed without first having been
assigned a value. The parameter contains the name of the global. *)
val empty : string -> 'a t
(** Returns an new named empty global. The name of the global can be any
string. It identifies the global and makes debugging easier. *)
val name : 'a t -> string
(** Retrieve the name of a global. *)
val set : 'a t -> 'a -> unit
(** Set the global value contents. *)
val get : 'a t -> 'a
(** Get the global value contents - raise Global_not_initialized if not
defined. *)
val undef : 'a t -> unit
(** Reset the global value contents to undefined. *)
val isdef : 'a t -> bool
(** Return [true] if the global value has been set. *)
val opt : 'a t -> 'a option
(** Return [None] if the global is undefined, else [Some v] where v is the
current global value contents. *)