Bad idea checking rendered status in HtmlBasicRenderer.getChildren()

Question

com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.getChildren() looks at all its children and only returns those that have their rendered attribute set to true. This is a bad idea, because the rendered property of a child may be a value binding that depends on the actual encoding of a sibling component that comes before it.
A case in point is an assignment component, such as I describe in http://forum.java.sun.com/thread.jspa?threadID=563036 . This component sets a value binding variable when it is rendered. If a subsequent component references this value binding in its rendered property, then the value will not have been properly set when com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.getChildren() attempts to collect children.
One workaround is wildly inefficient: have UIAssignment perform the assignment in its own isRendered() method. (This also assumes that getChildren() will call each isRendered() in the correct order.)
A better workaround would be to create a custom renderer for UIData that is more forgiving to value-binding rendered properties.
Would it hurt for the JSF specification to simply state that whether a component is rendered may not be conclusively determined until after all preceding components have been rendered? This would allow my UIAssignment to work, and would moreover allow any UIComponent.rendered to feel safe that any value binding it depends on will have been called if it was to be set in a preceding component's encoding routines.
Garret

Answer 1

I've created a nice workaround that adds a benefit. UIAssignment now allows children and has scope semantics---all components relying on the assignment should be children of the UIAssignment.
To pull this off, UIAssignment returns true for getRendersChildren(). Now, HtmlBasicRenderer or any other code should allow UIAssignment to determine for itself whether its children should be encoded. This way UIAssignment can make sure the assignment has been performed before checking each child's rendered status.
An added benefit of this change is that UIAssignment can have true scope semantics, setting the value before encoding/decoding, and restoring the value to its previous state afterwards.
This won't help other components that rely on activity in previous sibling encodings for determining rendered status, though. But I've fixed my UIAssignment problem.
Garret