(* * ObservableFun - Observer Design Pattern, Functional Interface v0.1 * Copyright (C) 2007 Quôc Peyrot * * 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 following special exception. * * As a special exception to the GNU Library General Public License, you * may link, statically or dynamically, a "work that uses the Library" * with a publicly distributed version of the Library to produce an * executable file containing portions of the Library, and distribute * that executable file under terms of your choice, without any of the * additional requirements listed in clause 6 of the GNU Library General * Public License. By "a publicly distributed version of the Library", * we mean either the unmodified Library as distributed, or a * modified version of the Library that is distributed under the * conditions defined in clause 3 of the GNU Library General Public * License. This exception does not however invalidate any other reasons * why the executable file might be covered by the GNU Library General * Public 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 *) (* Observer Design Pattern - Functional Implementation: An Observable value is a value attached to a set of callbacks which are automatically called whenever the value is modified. When adding a callback, an identifier is provided to be able to remove it without having access to the callback originally used. Example: let observable0 = Observable.make 0 in let callback value = print_endline (string_of_int value) in let observable1 = Observable.add_observer "mycallback" callback observable0 in let observable2 = Observable.set 42 observable1 in let observable3 = Observable.remove_observer "mycallback" in let observable4 = Observable.set 51 in exit 1 *) module Observable : sig type 'a t val make : 'a -> 'a t val get : 'a t -> 'a val set : 'a -> 'a t -> 'a t val add_observer : string -> ('a -> unit) -> 'a t -> 'a t val remove_observer : string -> 'a t -> 'a t val remove_all_observers : 'a t -> 'a t val call_observers : 'a t -> unit end
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