JSP.B.2 Processing taglib Directives

JSP.B.2 Processing taglib Directives

A strict 1-pass implementation would make custom actions visible only after their corresponding taglib directive appears. But this semantics can lead to the situation where a JSP page author is staring at a JSP page fragment with the assumption that a taglib directive appears before, when it really is included after. The semantics of Section JSP.2.7.7 are designed to support an efficient implementation while minimizing JSP page author mistakes.

An implementation can still work in a 1-pass manner; it only needs to remember all the prefixes it has found and make the assumption that taglib directives appear before their use. But, if it later discovers that a taglib directive is defining a prefix that was used previously, then it can cause a translation error.