Stefano Cazzola wrote:I supposed it was a standard behavior and that it was possible also with custom tags.
Ahhhh! This is an important distinction. HTML tags, and all other client-side markup is just template text to the JSP engine. It could be the Magna Carta as far as the JSP engine is concerned -- it doesn't apply any semantics to it whatsoever.
However I found a solution (quite verbose
The more standard way is to store the output of the custom tag in a scoped variable, and then use the EL to supply that value as the attribute value.