/*
* object.watch v0.0.1: Cross-browser object.watch
* http://code.eligrey.com/object.watch/
*
* By Elijah Grey, http://eligrey.com
*
* A shim that partially implements object.watch and object.unwatch
* in browsers that have accessor support.
*
* Public Domain.
* NO WARRANTY EXPRESSED OR IMPLIED. USE AT YOUR OWN RISK.
*/

// object.watch
if (!Object.prototype.watch)
	Object.prototype.watch = function (prop, handler) {
		var oldval = this[prop], newval = oldval,
		getter = function () {
			return newval;
		},
		setter = function (val) {
			oldval = newval;
			return newval = handler.call(this, prop, oldval, val);
		};
		if (delete this[prop]) { // can't watch constants
			if (Object.defineProperty) // ECMAScript 5
				Object.defineProperty(this, prop, {
					get: getter,
					set: setter
				});
			else if (Object.prototype.__defineGetter__ && Object.prototype.__defineSetter__) { // legacy
				Object.prototype.__defineGetter__.call(this, prop, getter);
				Object.prototype.__defineSetter__.call(this, prop, setter);
			}
		}
	};

// object.unwatch
if (!Object.prototype.unwatch)
	Object.prototype.unwatch = function (prop) {
		var val = this[prop];
		delete this[prop]; // remove accessors
		this[prop] = val;
	};