Opt in to "even lazier" behavior by setting lazyRegister to "max". …

…This was done to preserve compatibility with the existing feature. Specifically, when "max" is used, setting `is` in `beforeRegister` and defining `factoryImpl` may only be done on an element's prototype and not its behaviors. In addition, the element's `beforeRegister` is called *before* its behaviors' `beforeRegisters` rather than *after* as in the normal case.
Polymer · Jul 22, 2016 · b271a88 · b271a88
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Showing 6 changed files with 88 additions and 19 deletions.
diff --git a/src/lib/base.html b/src/lib/base.html
@@ -30,6 +30,24 @@
 
     // `this` context is a prototype, not an instance
     registerCallback: function() {
+      /*
+        When lazyRegister is 'max' defer all behavior work until first element
+        creation. 
+        When set, a behavior cannot setup an element's `is` or 
+        custom constructor via defining `factoryImpl`.
+        We do call beforeRegister on the prototype to preserve
+        the ability to use it in ES6. This orders the element 
+        prototype's `beforeRegister` before behaviors' rather than after
+        as in the normal case.
+      */
+      if (settings.lazyRegister === 'max') {
+        if (this.beforeRegister) {
+          this.beforeRegister();
+        }
+      } else {
+        this._desugarBehaviors(); // abstract
+        this._doBehavior('beforeRegister'); // abstract
+      }
       this._registerFeatures();  // abstract
       if (!settings.lazyRegister) {
         this.ensureRegisterFinished();
@@ -59,11 +77,12 @@
 
     _ensureRegisterFinished: function(proto) {
       if (proto.__hasRegisterFinished !== proto.is || !proto.is) {
-        // NOTE: since all behavior is here, this means
-        // custom constructor and `is` cannot be done in a behavior
-        // when lazyRegister is true.
-        proto._desugarBehaviors(); // abstract
-        proto._doBehavior('beforeRegister'); // abstract
+        // apply behavior's beforeRegister at first instance time
+        // IFF `lazyRegister` is 'max'
+        if (settings.lazyRegister === 'max') {
+          proto._desugarBehaviors(); // abstract
+          proto._doBehaviorOnly('beforeRegister'); // abstract
+        }
         proto.__hasRegisterFinished = proto.is;
         if (proto._finishRegisterFeatures) {
           proto._finishRegisterFeatures();

diff --git a/src/micro/behaviors.html b/src/micro/behaviors.html
@@ -130,6 +130,13 @@
       this._invokeBehavior(this, name, args);
     },
 
+    // note: repeating logic here to avoid fn call.
+    _doBehaviorOnly: function(name, args) {
+      for (var i=0; i < this.behaviors.length; i++) {
+        this._invokeBehavior(this.behaviors[i], name, args);
+      }
+    },
+
     _invokeBehavior: function(b, name, args) {
       var fn = b[name];
       if (fn) {

diff --git a/test/runner.html b/test/runner.html
@@ -25,6 +25,8 @@
       'unit/dom-module-inline.html',
       'unit/async.html',
       'unit/behaviors.html',
+      'unit/behaviors.html?lazyRegister=true',
+      'unit/behaviors.html?lazyRegister=max',
       'unit/template.html',
       'unit/template-whitespace.html',
       'unit/ready.html',

diff --git a/test/smoke/es6.html b/test/smoke/es6.html
@@ -0,0 +1,31 @@
+<!doctype html>
+<html>
+<head>
+  <script src="../../../webcomponentsjs/webcomponents.js"></script>
+  <script>
+    Polymer = {lazyRegister: true};
+  </script>
+  <link rel="import" href="../../polymer.html">
+</head>
+<body>
+  <dom-module id="my-element">
+    <template>
+      es6
+    </template>
+  </dom-module>
+
+   <script>
+    class MyElement {
+      beforeRegister() {
+        this.is = 'my-element';
+      }
+    }
+
+    Polymer(MyElement);
+  </script>
+
+
+<my-element></my-element>
+
+</body>
+</html>
diff --git a/test/unit/behaviors-elements.html b/test/unit/behaviors-elements.html
@@ -249,14 +249,19 @@
     }
   };
 
-  Polymer({
+  try {
 
-    behaviors: [
-      Polymer.registerBehavior
-    ],
+    Polymer({
 
-    as: 'behavior-as-is'
+      behaviors: [
+        Polymer.registerBehavior
+      ],
 
-  });
+      as: 'behavior-as-is'
+
+    });
+  } catch(e) {
+    window.behaviorAsIsFail = true;
+  }
 
 </script>
diff --git a/test/unit/behaviors.html b/test/unit/behaviors.html
@@ -53,13 +53,17 @@
   });
 
   test('beforeRegister behavior', function() {
-    var el = document.createElement('behavior-as-is');
-    assert.equal(el.is, 'behavior-as-is');
-    assert.ok(el.$.content);
-    el.prop = 42;
-    assert.isTrue(el.propChanged1Called);
-    assert.isTrue(el.propChanged2Called);
-    assert.isTrue(el.hasAttribute('attr'));
+    if (Polymer.Settings.lazyRegister === 'max') {
+      assert.isTrue(window.behaviorAsIsFail, 'Setting `is` in a behavior did not fail when lazyRegister: `max` set');
+    } else {
+      var el = document.createElement('behavior-as-is');
+      assert.equal(el.is, 'behavior-as-is');
+      assert.ok(el.$.content);
+      el.prop = 42;
+      assert.isTrue(el.propChanged1Called);
+      assert.isTrue(el.propChanged2Called);
+      assert.isTrue(el.hasAttribute('attr'));
+    }
   });
 
 });
@@ -127,7 +131,7 @@
     assert.equal(el.attributes.user.value, 'user', 'Behavior hostAttribute overrode user attribute');
   });
 
-  test('behaviour is null generates warning', function() {
+  test('behavior is null generates warning', function() {
     var warned = false, oldWarn = Polymer.Base._warn;
     Polymer.Base._warn = function (message) {
       assert.match(message, /behavior is null/);
@@ -139,6 +143,7 @@
         null
       ]
     });
+    document.createElement('behavior-null');
     assert.equal(warned, true, 'Null behaviour should generate warning');
     Polymer.Base._warn = oldWarn;
   });