Updating Polymer to derive from custom elements.

pkg/polymer/lib/src/loader.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of polymer;
 
 /** Annotation used to automatically register polymer elements. */
 class CustomTag {
   final String tagName;
-  const CustomTag(this.tagName);
+  final Type type;
+  const CustomTag(this.tagName, {Type type}) : this.type = type;

[Siggi Cherem (dart-lang), 2013/10/10 22:25:51]

how about:

const CustomTag(this.tagName, {this.type});

?

[blois, 2013/10/11 22:40:12]

Done.

 }
 
 /**
  * Metadata used to label static or top-level methods that are called
  * automatically when loading the library of a custom element.
  */
 const initMethod = const _InitMethodAnnotation();
 
 /**
  * Initializes a polymer application as follows:
  *   * set up up polling for observable changes
  *   *  initialize MDV
  *   *  for each library in [libraries], register custom elements labeled with
  *      [CustomTag] and invoke the initialization method on it.
  *
  * The initialization on each library is either a method named `main` or
  * a top-level function and annotated with [initMethod].
  *
  * The urls in [libraries] can be absolute or relative to [srcUrl].
  */
 void initPolymer(List<String> libraries, [String srcUrl]) {
   runMicrotask(() {
     // DOM events don't yet go through microtasks, so we catch those here.
     new Timer.periodic(new Duration(milliseconds: 125),
         (_) => performMicrotaskCheckpoint());
 
     // TODO(jmesserly): mdv should use initMdv instead of mdv.initialize.
     mdv.initialize();
-    registerCustomElement('polymer-element', () => new PolymerDeclaration());
+    document.register(PolymerDeclaration._TAG, PolymerDeclaration);
 
     for (var lib in libraries) {
       _loadLibrary(lib, srcUrl);
     }
 
     // TODO(jmesserly): this should be in the custom_element polyfill, not here.
     // notify the system that we are bootstrapped
     document.body.dispatchEvent(
         new CustomEvent('WebComponentsReady', canBubble: true));
   });
@@ skipping 33 matching lines @@
   // Search top-level functions marked with @initMethod
   for (var f in lib.functions.values) {
     _maybeInvoke(lib, f);
   }
 
   for (var c in lib.classes.values) {
     // Search for @CustomTag on classes
     for (var m in c.metadata) {
       var meta = m.reflectee;
       if (meta is CustomTag) {
-        Polymer._registerClassMirror(meta.tagName, c);
+        Polymer.register(meta.tagName, meta.type);

[Jennifer Messerly, 2013/10/10 22:35:17]

it's a bummer that we're going to have a breaking change that Type is required
and then undo it after a few weeks...

Here's a workaround--actually works as far as I can tell :)

We should probably send a patch because the fix seems straightforward in
dart2js. It appears to be a 1-liner: `Type get reflectedType =>
createRuntimeType(_mangledName);` inside JsClassMirror.



// Horrible hack to work around: http://dartbug.com/12607
Type getReflectedTypeWorkaround(ClassMirror cls) {
  // On Dart VM, just return reflectedType.
  if (1.0 is! int) return cls.reflectedType;

  var mangledName = reflect(cls).getField(_mangledNameField).reflectee;
  Type type = _jsHelper.invoke(#createRuntimeType, [mangledName]).reflectee;
  return type;
}

final LibraryMirror _jsHelper =
    currentMirrorSystem().libraries[Uri.parse('dart:_js_helper')];

final Symbol _mangledNameField = () {
  var jsClassMirrorMirror = reflect(reflectClass(ClassMirror)).type;
  for (var name in jsClassMirrorMirror.variables.keys) {
    if (MirrorSystem.getName(name) == '_mangledName') return name;
  }
}();

[blois, 2013/10/11 22:40:12]

Evil. Done.

[Siggi Cherem (dart-lang), 2013/10/14 17:02:52]

Now that you have the workaround, can't we get rid of the 'type' field in
@CustomType?

       }
     }
 
     // TODO(sigmund): check also static methods marked with @initMethod.
     // This is blocked on two bugs:
     //  - dartbug.com/12133 (static methods are incorrectly listed as top-level
     //    in dart2js, so they end up being called twice)
     //  - dartbug.com/12134 (sometimes "method.metadata" throws an exception,
     //    we could wrap and hide those exceptions, but it's not ideal).
   }
@@ skipping 17 matching lines @@
     print("warning: methods marked with @initMethod should take no "
         "arguments, ${method.simpleName} expects some.");
     return;
   }
   obj.invoke(method.simpleName, const []);
 }
 
 class _InitMethodAnnotation {
   const _InitMethodAnnotation();
 }