robotlolita · November 23, 2011 21:59 · Nov 23, 2011
diff --git a/multiple-delegation.js b/multiple-delegation.js
@@ -0,0 +1,51 @@
+
+var boo = require('boo')
+
+
+var Delegate = {
+
+  // Makes the given property a getter, that will try the
+  // objects in order until it finds a suitable one.
+  //
+  // proxy :: String → Object
+  proxy:
+  function proxy(property) {
+    var local = "_" + property
+    Object.defineProperty(this, property, {
+      get:          delegate_property
+    , set:          function(value){ this[local] = value }
+    , configurable: true
+    , enumerable:   true })
+
+    return this
+
+    function delegate_property() { var i
+      if (local in this)     return this[local]
+      if (!this.proto_list)  return undefined
+      i = this.proto_list.length
+      while (i--)
+        if (property in this.proto_list[i])
+          return this.proto_list[i][property] }}
+}
+
+
+var foo = { x: 1, z: 1 }
+var bar = { y: 2 }
+var baz = boo.clone(Delegate, {
+  proto_list: [foo, bar]
+, _z: 2
+})
+
+baz.proxy('x').proxy('y').proxy('z')
+
+console.log(baz.x, baz.y, baz.z)
+// 1 2 2
+
+baz.proto_list = []
+console.log(baz.x, baz.y, baz.z)
+// undefined undefined 2
+
+baz.proto_list = [foo, bar]
+foo.y = 1
+console.log(baz.x, baz.y, baz.z)
+// 1 2 2   -- bar still has a higher precedence :3