/**
* mixin Class.Watchable
*
* - watch(property, handler) -> Object
* - unwatch(property) -> Object
*
* A convenient mixin for a naive simulation of Mozilla's proprietary Object.prototype.watch/unwatch
* "watch" interval can be set via static Class.Watchable.INTERVAL (defaults to 100ms)
* "watched" object is polluted with 2 properties: __watchable and __callback
* handler is invoked with 3 arguments - propertyName, oldValue, newValue
*
* var Person = Class.create(Class.Watchable, {
* initialize: function(name) {
* this.name = name;
* },
* speak: function(msg) {
* return [this.name, msg].join(': ');
* }
* })
*
* var jdd = new Person('John');
*
* jdd.watch('name', console.log);
*
* jdd.name; // "John"
* jdd.name = "Juriy"; // fires handler associated with "name", passing it: prop, oldValue, newValue
*
*/
Class.Watchable = Class.create({
watch: function(prop, handler) {
// isFunction will return true for regexp (but it's too ugly to fix it here)
if (Object.isUndefined(prop) || !Object.isFunction(handler))
throw new TypeError('Wrong arguments supplied');
if (!this.__watchable) this.__watchable = { };
var w = this.__watchable;
if (!w.clone) w.clone = { };
w.clone[prop] = this[prop];
if (!w.handlers) w.handlers = { };
if (!w.handlers[prop]) w.handlers[prop] = [ ];
if (!w.handlers[prop].include(handler)) w.handlers[prop].push(handler);
if (!w.timer)
w.timer = setInterval(this.__callback.bind(this), Class.Watchable.INTERVAL);
return this;
},
unwatch: function(prop, handler) {
var w = this.__watchable;
if (w.clone && w.clone[prop])
if (handler)
w.handlers[prop] = w.handlers[prop].without(handler);
else
w.handlers[prop] = [ ];
return this;
},
__callback: function() {
var oldValue, handlers, w = this.__watchable;
for (var prop in w.clone) {
if (w.clone[prop] != this[prop]) {
oldValue = w.clone[prop];
w.clone[prop] = this[prop];
handlers = w.handlers[prop];
for (var i=0, l=handlers.length; i<l; i++) {
handlers[i].call(handlers[i], prop, oldValue, this[prop]);
}
}
}
}
})
Class.Watchable.INTERVAL = 100;
