Confused about IAdaptable with IActionFilters

Question

I'm confuse about IAdaptable and related classes. Which class is the adapter, the adaptee, the adaptable type?

[Context]

I have a context menu for entries of a table/tree viewer. Certain actions in the context menu must not be visible depending on the state of the respective object in the viewer (i.e. attribute value of a row in the table viewer).

I can achieve this with a config like this in plugin.xml:

<extension
         point="org.eclipse.ui.popupMenus">
      <objectContribution
            adaptable="false"
            id="<some_id>"
            objectClass="<object_class_of_viewer_entry>">
            <visibility>
               <objectState name="buildable" value="true"/>
             </visibility>
         <action
               class="<my_action_class>"

However, this only works if the object class implements org.eclipse.ui.IActionFilter.

[Problem]

My object class can't implement IActionFilter, I don't want to change its interface. Hence, I need to work around that using the IAdaptable mechanism.

Reading the Eclipse documentation left me all puzzled with terms (adapter, the adaptee, adaptable type) and I'm still confused about how to go about my problem.

The object class (referred to by in the above config) must remain untouched.

My approach was the following.

<extension
         point="org.eclipse.core.runtime.adapters">
      <factory
            adaptableType="<object_class_of_viewer_entry>"
            class="MyFactory">
         <adapter
               type="org.eclipse.ui.IActionFilter">
         </adapter>
      </factory>
   </extension>

MyFactory is like this:

public class MyFactory implements IAdapterFactory {
  private static final Class[] types = {
    <object_class_of_viewer_entry>.class,
  };

  @Override
  public Object getAdapter(Object adaptableObject, Class adapterType) {
    return new <class_that_implements_IActionFilter>((<object_class_of_viewer_entry>) adaptableObject);
  }

  @Override
  public Class[] getAdapterList() {
    return types;
  }
}

What's wrong about this? Where did I miss something?

Answer 1

Turns out everything, well, almost everything, was correct. I had simply mixed up interface and implementation of object_class_of_viewer_entry in the plugin.xml.

Two articles that helped: http://www.eclipsezone.com/articles/what-is-iadaptable/ and http://wiki.eclipse.org/FAQ_How_do_I_use_IAdaptable_and_IAdapterFactory%3F