Available since OmniFaces 1.0
<o:methodParam> is a tag handler that can be used to pass a method expression as attribute into a Facelets tag. By default this is not possible, and the expression that's intended to be a method expression will be created and made available as a value expression.
This handler wraps a value expression that's actually a method expression by another value expression that returns a method expression that gets the value of first value expression, which as "side-effect" executes the original method expression. This somewhat over-the-top chain of wrapping is done so a method expression can be passed as attribute into a Facelet tag.
This page demonstrates the passing of an EL reference to a method to a Facelets tag in a variety of
different ways. Note that the
<demo:xxx> tags in the example are purely for demonstration,
it should represent your own custom Facelets tag.