Element Factories

org.eclipse.ui.elementFactories

This extension point is used to add element factories to the workbench. An element factory is used to recreate IAdaptable objects which are persisted during workbench shutdown.

As an example, the element factory is used to persist editor input. The input for an editor must implement org.eclipse.ui.EditorInput. The life cycle of an IEditorInput within an editor has a number of phases.

  1. The initial input for an editor is passed in during editor creation.

  2. On shutdown the workbench state is captured. In this process the workbench will create a memento for each open editor and its input. The input is saved as a two part memento containing a factory ID and any primitive data required to recreate the element on startup. For more information see the documentation on org.eclipse.ui.IPersistableElement.

  3. On startup the workbench state is read and the editors from the previous session are recreated. In this process the workbench will recreate the input element for each open editor. To do this it will map the original factory ID for the input element to a concrete factory class defined in the registry. If a mapping exists, and the factory class is valid, an instance of the factory class is created. Then the workbench asks the factory to recreate the original element from the remaining primitive data within the memento. The resulting IAdaptable is cast to an IEditorInput and passed to the new editor.

<!ELEMENT extension (factory*)>

<!ATTLIST extension

point CDATA #REQUIRED

id    CDATA #IMPLIED

name  CDATA #IMPLIED>


<!ELEMENT factory EMPTY>

<!ATTLIST factory

id    CDATA #REQUIRED

class CDATA #REQUIRED>


The following is an example of an element factory extension: 

   
<extension 
        point = 
"org.eclipse.ui.elementFactories"
>
 
        
<factory 
           id =
"com.xyz.ElementFactory"
 
           class=
"com.xyz.ElementFactory"
>
 
        
</factory>
 
    
</extension>

The value of the class attribute must be a fully qualified name of a class that implements org.eclipse.ui.IElementFactory. An instance of this class must create an IAdaptable object from a workbench memento.

The workbench provides an IResource factory. Additional factories should be added to recreate other IAdaptable types commonly found in other object models, such as the Java Model.