Refactor the event-generation code to locate it in systemhtml.py.

client/dom/scripts/systemhtml.py

Index: client/dom/scripts/systemhtml.py
diff --git a/client/dom/scripts/systemhtml.py b/client/dom/scripts/systemhtml.py
index 4c4945780abf44ed016d8882e35531a62661add9..da6de23275d40a85edcea95a266fbea98e78a4e9 100644
--- a/client/dom/scripts/systemhtml.py
+++ b/client/dom/scripts/systemhtml.py
@@ -383,6 +383,11 @@ _html_event_names = {
   'webkitTransitionEnd': 'transitionEnd'
 }
 
+# These classes require an explicit declaration for the "on" method even though
+# they don't declare any unique events, because the concrete class hierarchy
+# doesn't match the interface hierarchy.
+_html_explicit_event_classes = set(['DocumentFragment'])
+
 def _OnAttributeToEventName(on_method):
   event_name = on_method.id[2:]
   if event_name in _on_attribute_to_event_name_mapping:
@@ -496,6 +501,14 @@ class HtmlSystemShared(object):
   def _ImplClassName(self, type_name):
     return '_' + type_name + 'Impl'
 
+  def GetEventAttributes(self, interface):
+    events =  set([attr for attr in interface.attributes
+                   if self._generator._IsEventAttribute(interface, attr)])
+
+    # Hack to generate no-op Element events for DocumentFragment.

[Jacob, 2012/03/07 23:24:05]

this comment can now be removed.

[nweiz, 2012/03/08 01:03:51]

Done.

+    if events or interface.id in _html_explicit_event_classes:
+      return events
+
 class HtmlSystem(System):
 
   def __init__(self, templates, database, emitters, output_dir, generator):
@@ -628,6 +641,9 @@ class HtmlDartInterfaceGenerator(DartInterfaceGenerator):
         CTOR=self._interface.id,
         TYPE=DartType(element_type))
 
+    events = self._shared.GetEventAttributes(self._interface)
+    if events != None: self.AddEventAttributes(events)

[Jacob, 2012/03/07 23:24:05]

I believe we're using the style of placing the if clause on the next line.

[nweiz, 2012/03/08 01:03:51]

Done.

+
   def AddAttribute(self, getter, setter):
     html_getter_name = self._shared.RenameInHtmlLibrary(
       self._interface, getter.id, 'get:')
@@ -758,6 +774,9 @@ class HtmlFrogClassGenerator(FrogInterfaceGenerator):
     if constructor_info:
       self._EmitFactoryProvider(interface_name, constructor_info)
 
+    events = self._shared.GetEventAttributes(interface)
+    if events != None: self.AddEventAttributes(events)

[Jacob, 2012/03/07 23:24:05]

why not just
if events:
  self.AddEventAttributes(events)

[nweiz, 2012/03/08 01:03:51]

Because we want to run AddEventAttributes even if events is empty.

[Jacob, 2012/03/08 18:38:09]

same comment as above for all cases where == set() is used

+
   def _EmitFactoryProvider(self, interface_name, constructor_info):
     template_file = 'factoryprovider_%s.darttemplate' % interface_name
     template = self._system._templates.TryLoad(template_file)
@@ -1237,6 +1256,9 @@ class HtmlDartiumInterfaceGenerator(object):
     if constructor_info:
       self._EmitFactoryProvider(interface_name, constructor_info)
 
+    events = self._shared.GetEventAttributes(self._interface)
+    if events != None: self.AddEventAttributes(events)
+
   def _EmitFactoryProvider(self, interface_name, constructor_info):
     template_file = 'factoryprovider_%s.darttemplate' % interface_name
     template = self._system._templates.TryLoad(template_file)