Updating the ViewModel to expose findValue as an alternative to paren…

…tValues array. This enables scenarios where you can find values on demand and not purely only when the view model is initialized.

Also renaming __events to _events. There's no need to double underscore a private value.

src/ViewModel.ts

@@ -2,48 +2,59 @@ import EventGroup = require('./EventGroup');
 
 class ViewModel {
     isViewModel = true;
-
+    parent: any;
     parentValues = [];
 
-    __events: EventGroup;
+    _events: EventGroup;
 
     private static __instanceCount = 0;
     private __id = ViewModel.__instanceCount++;
 
     public constructor(data?: any) {
-        this.__events = new EventGroup(this);
-        this.__events.declare('change');
+        this._events = new EventGroup(this);
+        this._events.declare('change');
 
         if (data) {
             this.setData(data, false);
         }
     }
 
-    public initialize() {
-        this.setData(this, false, true);
-
-        for (var i = 0; i < this.parentValues.length; i++) {
-            var args = { name: this.parentValues[i], val: null };
+    public findValue(valueName) {
+        var val = this[valueName];
 
-            this.__events.raise('findValue', args, true);
+        if (!val) {
+            var args = { name: valueName, val: null };
+
+            this._events.raise('findValue', args, true);
 
             if (args.val !== null) {
-                var data = {};
-                data[args.name] = args.val;
-                this.setData(data, false, true);
+                val = args.val;
             }
             else {
                 throw "Unable to find value: " + args.name;
-            }
+            }            
+        }
+
+        return val;
+    }
+
+    public initialize() {
+
+        // The parentValues concept is not great because it's not predictable.
+        // This should be removed, but will leave it for now to not break anything.
+        for (var i = 0; i < this.parentValues.length; i++) {
+            this[this.parentValues[i]] = this.findValue(this.parentValues[i]);
         }
 
         this.onInitialize();
+
+        this.setData(this, false, true);
     }
 
     public onInitialize() {}
 
     public dispose() {
-        this.__events.dispose();
+        this._events.dispose();
         this.onDispose();
     }
 
@@ -59,12 +70,12 @@ class ViewModel {
 
                 if (oldValue !== newValue || forceListen) {
                     if (oldValue && EventGroup.isDeclared(oldValue, 'change')) {
-                        this.__events.off(oldValue, 'change', this.change);
+                        this._events.off(oldValue, 'change', this.change);
                     }
                     this[key] = newValue;
                     hasChanged = true;
                     if (newValue && EventGroup.isDeclared(newValue, 'change')) {
-                        this.__events.on(newValue, 'change', this.change);
+                        this._events.on(newValue, 'change', this.change);
                     }
                 }
             }
@@ -76,7 +87,7 @@ class ViewModel {
     }
 
     public change(args ? : any) {
-        this.__events.raise('change', args);
+        this._events.raise('change', args);
     }
 }