Re: [jsr-314-open] Fwd: Allow multiple taglib.xml files for the same namespace

Forwarded from dev list. Lincoln Baxter III http://ocpsoft.com http://scrumshark.com Keep it simple. ---------- Forwarded message ---------- From: "Matthias Berndt" <matthias.berndt(a)systemtrap.net&gt; Date: Nov 13, 2009 10:01 AM Subject: Allow multiple taglib.xml files for the same namespace To: <dev(a)javaserverfaces.dev.java.net&gt; Hello, first I'd like to explain my intention. The scenario is writing multiple JSF components being bundled in more than one java archive. Each java archive has its own taglib.xml descriptor so you can use them separately. These components belong to the same project or organisation and should be published within the same namespace. This isn't possible with facelets at the moment and is a known issue to facelets. See: https://facelets.dev.java.net/issues/show_bug.cgi?id=118 To support this scenario I'm aware of 3 possible solutions. The first one is merging the needed java archives especially the taglib.xml. I think this one is bad because the separation between the component projects is destroyed. The second one is merging the taglib definitions while being processed by FaceletTaglibConfigProcessor#processTagLibrary(). In line 308 a new TagLibraryImpl is created for every facelet-taglib element. This can be extended to use an already existing TagLibraryImpl for a specific namespace. This extension requires about 10 to 15 lines of code. As a result there will be one TagLibraryImpl for multiple facelet-taglib elements with the same namespace. The third one, my preferd one, is using the existing CompositeTagLibrary. As a result and in contrast to the second method each facelet-taglib element will be represented by a TagLibraryImpl and combined by CompositeTagLibrary. This requires only a minor change. In FaceletTaglibConfigProcessor#processTagLibrary() in line 318 the created TagLibraryImpl is added to the compiler. Compiler#addTagLibrary() tests if the given library is already known to the compiler. Subsequently this is done by using equals() and hashCode() in AbstractTagLibrary. At the moment hashCode() is implemented to use nothing except the namespace. If there are multiple TagLibraryImpl with the same namespace only one will be included in the compiler. The rest is thrown away. By extending hashCode() to use this.factories and this.functions in the calculation multiple TagLibraryImpl with different tags etc. can coexist. IMO it makes sense by reason taglibs are not equal only because they define the same namespace. CompositeTagLibrary handles this very well so no other changes are required. I attached a patch to modify AbstractTagLibrary#hashCode(). The algorithm is base on Joshua Bloch's Effective Java. The existing test cases are not harmed and apologize my self not writing a specific test case. I don't like to call it a patch because it's so stupidly simple, but I'd be glad if something like it could be shipped with JSF2 to provide this feature. kind regards, Matthias Berndt --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscribe(a)javaserverfaces.dev.java.net For additional commands, e-mail: dev-help(a)javaserverfaces.dev.java.net