ListenerMixin

lumbar.json

@@ -19,6 +19,7 @@
         "src/date-formatting.js",
         "src/common/Class.js",
         "src/common/EmitterMixin.js",
+        "src/common/ListenerMixin.js",
         "src/common/Popover.js",
         "src/common/CoordCache.js",
         "src/common/DragListener.js",

src/common/ListenerMixin.js

@@ -0,0 +1,61 @@
+
+/*
+Utility methods for easily listening to events on another object,
+and more importantly, easily unlistening from them.
+*/
+var ListenerMixin = FC.ListenerMixin = (function() {
+	var guid = 0;
+	var ListenerMixin = {
+
+		listenerId: null,
+
+		/*
+		Given an `other` object that has on/off methods, bind the given `callback` to an event by the given name.
+		The `callback` will be called with the `this` context of the object that .listenTo is being called on.
+		Can be called:
+			.listenTo(other, eventName, callback)
+		OR
+			.listenTo(other, {
+				eventName1: callback1,
+				eventName2: callback2
+			})
+		*/
+		listenTo: function(other, arg, callback) {
+			if (typeof arg === 'object') { // given dictionary of callbacks
+				for (var eventName in arg) {
+					if (arg.hasOwnProperty(eventName)) {
+						this.listenTo(other, eventName, arg[eventName]);
+					}
+				}
+			}
+			else if (typeof arg === 'string') {
+				other.on(
+					arg + '.' + this.getListenerNamespace(), // use event namespacing to identify this object
+					$.proxy(callback, this) // always use `this` context
+						// the usually-undesired jQuery guid behavior doesn't matter,
+						// because we always unbind via namespace
+				);
+			}
+		},
+
+		/*
+		Causes the current object to stop listening to events on the `other` object.
+		`eventName` is optional. If omitted, will stop listening to ALL events on `other`.
+		*/
+		stopListeningTo: function(other, eventName) {
+			other.off((eventName || '') + '.' + this.getListenerNamespace());
+		},
+
+		/*
+		Returns a string, unique to this object, to be used for event namespacing
+		*/
+		getListenerNamespace: function() {
+			if (this.listenerId == null) {
+				this.listenerId = guid++;
+			}
+			return '_listener' + this.listenerId;
+		}
+
+	};
+	return ListenerMixin;
+})();