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From Manfred Geiler <manfred.gei...@gmail.com>
Subject Re: svn commit: r225327 - /myfaces/api/trunk/src/java/javax/faces/component/UIComponentBase.java
Date Tue, 09 Aug 2005 11:27:12 GMT
Just had a look at the spec (i.e. javadoc) and the RI source code:
How we handled the List was absolutely correct IMO.
The problem you have, would also arise with the RI. So, I do not so a
reason to do this "trick" in the MyFaces implementation. The drawback
of your patch is: If someone has a List other than an ArrayList the
method will fail.

-Manfred


2005/8/3, Sylvain Vieujot <svieujot@apache.org>:
>  Hello Manfred,
>  
>  Here is a specific example where savestate would fail :
>  <x:saveState value="#{myLinkedList}/>
>  
>  The save state would return a List, and not a LinkedList.
>  So if you use somewhere in your code myLinkedList.pool(), it would fail.
>  In fact it fails earlier, as the saved value can't be coerced to a
> LinkedList.
>  
>  I think this is important as you expect the saveState to return exactly
> what you saved, and not a object with a different type.
>  
>  In my applications, I have a base backing bean that uses this scheme :
>  
>  public class BaseFace implements Serializable {
>  
>  public LinkedList<Object> getStates(){
>  return new LinkedList<Object>();
>  }
>  
>  /**
>  * Restore the states.
>  */
>  public void setStates(@SuppressWarnings("unused")
> LinkedList<Object> states) throws Exception{
>  // NoOp
>  }
>          ...
>  }
>  
>  It's quite nice because at you can extend this class easily and still have
> an easy job saving / restoring the state :
>  
>  public class BaseFaceForObjectWithUnid<T extends ObjectWithUnid> extends
> BaseFace {
>          ...
>  
>  @Override
>  public LinkedList<Object> getStates(){
>  LinkedList<Object> states = super.getStates();
>  states.add( object == null ? null : object.getUnid() );
>  return states;
>  }
>  
>  @Override
>  public void setStates(LinkedList<Object> states) throws Exception{
>  super.setStates(states);
>  setUnid(states == null ? null : (String)states.poll());
>  }
>          ...
>  }
>  
>  It worked fine until the related UIComponentBase had been modified.
>  So I limited the case for ArrayList.
>  
>  But I still have problems with this
> UIComponentBase.saveAttachedState code, as I guess similar
> problems with other types (like a custom class implementing List) could
> arrise.
>  What I understand is that we need this "trick" to check if the List doesn't
> contain any StateHolder.
>  If I'm right and if we still need that, then maybe we can do a recursive
> check for any StateHolder object, and if there is none, then just serialize
> the object.
>  
>  By the way, it's not exactly clear for me why we need to have a special
> treatment for StateHolders.
>  Could you clarify this for me please ?
>  
>  Thanks,
>  
>  Sylvain.
> 
>  
>  
>  On Wed, 2005-07-27 at 21:48 +0200, Manfred Geiler wrote: 
>  Sylvain,
> This change does not make much sense IMHO.
> Why do you check for ArrayList instead of List. There is only a List
> cast after that, so why not just check for List?
> Is there anything a LinkedList does not correctly implement from the
> List interface?!
> 
> -Manfred
> 
> 2005/7/26, svieujot@apache.org <svieujot@apache.org>:
> > Author: svieujot
> > Date: Tue Jul 26 08:25:26 2005
> > New Revision: 225327
> > 
> > URL: http://svn.apache.org/viewcvs?rev=225327&view=rev
> > Log:
> > Bugfix for savestate with a linkedlist (couldn't coerce a value of type
> "java.util.ArrayList" to type "java.util.LinkedList".
> > 
> > Modified:
> >
> myfaces/api/trunk/src/java/javax/faces/component/UIComponentBase.java
> > 
> > Modified:
> myfaces/api/trunk/src/java/javax/faces/component/UIComponentBase.java
> > URL:
> http://svn.apache.org/viewcvs/myfaces/api/trunk/src/java/javax/faces/component/UIComponentBase.java?rev=225327&r1=225326&r2=225327&view=diff
> >
> ==============================================================================
> > ---
> myfaces/api/trunk/src/java/javax/faces/component/UIComponentBase.java
> (original)
> > +++
> myfaces/api/trunk/src/java/javax/faces/component/UIComponentBase.java
> Tue Jul 26 08:25:26 2005
> > @@ -593,9 +593,9 @@
> > Object attachedObject)
> > {
> > if (attachedObject == null) return null;
> > - if (attachedObject instanceof List)
> > + if (attachedObject instanceof ArrayList)
> > {
> > - ArrayList lst = new
> ArrayList(((List)attachedObject).size());
> > + List lst = new
> ArrayList(((List)attachedObject).size());
> > for (Iterator it = ((List)attachedObject).iterator();
> it.hasNext(); )
> > {
> > lst.add(saveAttachedState(context, it.next()));
> > 
> > 
> >
> 
>

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