[jsr-314-open] Tree visit hints [Was: ADMIN: Final list of issues for JSF 2.0 and actions for each]

[Andy Schwartz]

Gang -

While reviewing this list with Ed earlier this week, Ed and I discussed 
very small issue that is not mentioned in the list but which we agreed 
to at least consider fixing for 2.0.  The issue is related to tree 
visiting and state saving.  I believe that it is likely that certain 
components may need to visit their children in a somewhat different 
manner for state saving purposes - eg. a UIData may take different steps 
when visiting children for state saving as opposed to say, rendering an 
Ajax response.  However, at the moment there is no way for a visitTree() 
implementation to know that state saving is being performed.  
visitTree() implementations do have access to the current phase id via 
the FacesContext, but of course state saving does not live in its own 
phase.  In order to provide a way to inform visitTree() implementations 
that state saving is being performed, I proposed (to Ed) that we add a 
new visit hint.

Currently we've got the following visit hints:

>   SKIP_UNRENDERED
>   SKIP_TRANSIENT
>   EXECUTE_LIFECYCLE


I would like to add this new hint:

>   EXECUTE_STATE_SAVING

While thinking about visit hints and UIData again, I got back to 
thinking about a use case that we had discussed in the past... Currently 
there is no way to tell components which visit their children multiple 
times (think UIData) not to bother performing iteration - ie. to only 
visit each child one time.  So, for example, in the UIData case, there 
is no way to tell the UIData component to not iterate over each row when 
visiting children.  At one point I had proposed a hint to provide 
control over this, but I never actually added this to the API.  After 
discussing this with my colleagues internally here, we realized that we 
have at least one case where we need this ability.  So, while I am in 
the VisitHint enum, I would like to also add the following new hint:

>   SKIP_ITERATION

I have opened up the following spec issue to track these requirements:

https://javaserverfaces-spec-public.dev.java.net/issues/show_bug.cgi?id=545

And have also uploaded a patch which adds both of these APIs (though for 
the most part leaves the implementation alone).

If anyone has comments/questions about either of these, please let me know.

Ed -

I realize that we did not discuss the SKIP_ITERATION proposal on our 
call.  Please let me know if you feel that it is inappropriate to add 
this.  I can  upload a new patch.

Andy