Return-Path: Delivered-To: apmail-jakarta-taglibs-user-archive@apache.org Received: (qmail 87076 invoked from network); 12 Sep 2002 16:58:43 -0000 Received: from unknown (HELO nagoya.betaversion.org) (192.18.49.131) by daedalus.apache.org with SMTP; 12 Sep 2002 16:58:43 -0000 Received: (qmail 23318 invoked by uid 97); 12 Sep 2002 16:59:15 -0000 Delivered-To: qmlist-jakarta-archive-taglibs-user@jakarta.apache.org Received: (qmail 23237 invoked by uid 97); 12 Sep 2002 16:59:13 -0000 Mailing-List: contact taglibs-user-help@jakarta.apache.org; run by ezmlm Precedence: bulk List-Unsubscribe: List-Subscribe: List-Help: List-Post: List-Id: "Tag Libraries Users List" Reply-To: "Tag Libraries Users List" Delivered-To: mailing list taglibs-user@jakarta.apache.org Received: (qmail 23181 invoked by uid 98); 12 Sep 2002 16:59:10 -0000 X-Antivirus: nagoya (v4218 created Aug 14 2002) Subject: Re: incorporating EL support From: Ryan Lubke To: Tag Libraries Users List In-Reply-To: <1031849139.29109.71.camel@jigra.begeek.com> References: <1031846557.29109.22.camel@jigra.begeek.com> <3D80BD53.98B249F8@labs.gte.com> <1031849139.29109.71.camel@jigra.begeek.com> Content-Type: text/plain Content-Transfer-Encoding: 7bit X-Mailer: Ximian Evolution 1.0.8 Date: 12 Sep 2002 12:58:30 -0400 Message-Id: <1031849911.1998.21.camel@rivendell> Mime-Version: 1.0 X-Spam-Rating: daedalus.apache.org 1.6.2 0/1000/N X-Spam-Rating: daedalus.apache.org 1.6.2 0/1000/N On Thu, 2002-09-12 at 12:45, Craig Longman wrote: > On Thu, 2002-09-12 at 12:14, peter lin wrote: > > > > > > You should know that JSP2.0 includes EL built in. the early access > > implementation of JSP2.0 uses JSTL's el. > > oh, ok. well, that's good news. i guess that splits my question into a > couple pieces: > > 1) jsp2.0 including EL, does that mean that the way one evaluates an EL > parameter will change, or that explicit evaluation will no longer be > necessary If using JSP 2.0 EL machinery, then you will not have to perform explicit evaluation in the tag library. The container will take care of this at runtime. > 2) is there a way of determining ( in a tag ) to determine what the JSP > level container we're executing in. then the tag (during a phase-in > period at least) could determine whether to explicitly evaluate it or > not. I think one approach is that if you don't want the container to evaluate EL expressions, you can package the app using a Servlet 2.3 deployment descriptor. JSP 2.0 containers will not perform EL evaluation in that case. I also believe that if you use JSTL EL, and you want JSTL to perform the EL evaluation you could also set a page property isELEnabled to false and the container will not evaluate EL expressions. I think there is a third option using a 2.4 deployment descriptor and using a jsp-property-group to disable EL across a set of pages identified by a URL pattern. If you let the JSP 2.0 container evaluate the EL in a JSTL tag, then it should be passed to JSTL as the evaluated value and you should have no problems. > > and a third question i suppose: > 3) is explicitly evaluating EL really as simple as calling > ExpressionEvaluatorManager.evaluate() (as below), or is there some other > prep/setup work i haven't noticed yet in the bowels of the current jstl > package? Will defer to someone more familiar with the EL machinery. > > > You may want to look at the draft spec to familiarize yourself with the > > changes that will occur when JSP2.0 is released. > > i'll try and track it down, thanks. > > > peter lin > > > > Craig Longman wrote: > > > > > > hi there, > > > > > > i'm just starting out with jsp/taglibs, and have decided to focus on > > > using the jstl as the basis for my efforts. it seems to provide exactly > > > what i needed, some basic, compatible tags to get started. > > > > > > it is clear, however, that i'm going to have to write my own tags to get > > > any serious work done. > > > > > > my question is this, i figure that if i'm going to standardize on the > > > jstl, then it only makes sense to standardize on the EL stuff also, i > > > prefer its style to the scriplet thingies, and its less typing. but, > > > i'm wondering what the preferred/recommended method is for doing this. > > > > > > i see in the src dist for the reference jstl that there are a couple of > > > classes that look promising to use. one is an interface > > > (ExpressionEvaluator) and then an implementing class > > > (ExpressionEvaluatorManager). using it appears to be as simple as this > > > (from tag/el/core/ForEachTag.java): > > > > > > if( begin_ != null ) > > > { > > > Object r = ExpressionEvaluatorManager.evaluate( > > > "begin", begin_, Integer.class, this, pageContext ); > > > if (r == null) > > > { > > > throw new NullAttributeException("forEach", "begin"); > > > } > > > begin = ((Integer) r).intValue(); > > > validateBegin(); > > > } > > > > > > it is acceptable to utilize this class in this manner for custom tags? > > > or is there a better/standard way. i have been unable to find any docs > > > that talk about using the standard EL in your own tags, but if anyone > > > has any pointers, i would greatly appreciate it. > > > > > > thanks, > > > > > > -- > > > > > > CraigL->Thx(); > > > Be Developer ID: 5852 > > > > > > ------------------------------------------------------------------------ > > > Name: signature.asc > > > signature.asc Type: application/pgp-signature > > > Description: This is a digitally signed message part > > > > -- > > To unsubscribe, e-mail: > > For additional commands, e-mail: > > > -- > > CraigL->Thx(); > Be Developer ID: 5852 > -- To unsubscribe, e-mail: For additional commands, e-mail: