Merge pull request #658 from twpayne/ol-object-events

ol.Object events

src/ol/object.exports

@@ -3,9 +3,11 @@
 @exportProperty ol.Object.prototype.get
 @exportProperty ol.Object.prototype.notify
 @exportProperty ol.Object.prototype.on
+@exportProperty ol.Object.prototype.onOnce
 @exportProperty ol.Object.prototype.set
 @exportProperty ol.Object.prototype.setOptions
 @exportProperty ol.Object.prototype.setValues
 @exportProperty ol.Object.prototype.un
+@exportProperty ol.Object.prototype.unByKey
 @exportProperty ol.Object.prototype.unbind
 @exportProperty ol.Object.prototype.unbindAll

src/ol/object.js

@@ -228,9 +228,22 @@ ol.Object.prototype.notifyInternal_ = function(key) {
  * @param {Function} listener The listener function.
  * @param {Object=} opt_scope Object is whose scope to call
  *     the listener.
+ * @return {?number} Unique key for the listener.
  */
 ol.Object.prototype.on = function(type, listener, opt_scope) {
-  goog.events.listen(this, type, listener, false, opt_scope);
+  return goog.events.listen(this, type, listener, false, opt_scope);
+};
+
+
+/**
+ * @param {string} type The event type.
+ * @param {Function} listener The listener function.
+ * @param {Object=} opt_scope Object is whose scope to call
+ *     the listener.
+ * @return {?number} Unique key for the listener.
+ */
+ol.Object.prototype.onOnce = function(type, listener, opt_scope) {
+  return goog.events.listenOnce(this, type, listener, false, opt_scope);
 };
 
 
@@ -308,6 +321,14 @@ ol.Object.prototype.un = function(type, listener, opt_scope) {
 };
 
 
+/**
+ * @param {?number} key Key.
+ */
+ol.Object.prototype.unByKey = function(key) {
+  goog.events.unlistenByKey(key);
+};
+
+
 /**
  * Removes all bindings.
  */