Handling component rendered state during postback

[Simon Kitching]

Hi,

A question on the user list reminded me of something I've been puzzled 
about for quite a while.

Does the JSF spec actually say that "rendered" EL expressions should be 
re-evaluated during postback? That's what MyFaces currently does, but it 
seems to me that the true/false state should really be part of the 
component's saved state and the restored value simply used during 
postback (and recalculated in render phase).

Does anyone know why in the current myfaces implementation each 
component recomputes its "rendered" state during postback by using its 
EL expression rather than using a value cached from the render phase?

Using a cached value would avoid some ugly problems with EL expressions 
being called before updateModel, as well as being a significant 
performance boost (rendered property tends to get queried several times 
during postback).

Regards, Simon