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From Eric W Hauser <ehau...@indiana.edu>
Subject Re: writing a custom tag that can use EL
Date Wed, 03 Sep 2003 18:30:01 GMT


On Wed, 3 Sep 2003, Felipe Leme wrote:

> - you *have* to add the code that evaluates the expression. With JSP 2.0 you 
> won't need to, it's done automatically

Although this is obviously a valid point, waiting for JSP 2.0 is not
really a good solution for the present.  Especially if you are someone who
is programming for a container such a Websphere, meaning that you probably
won't see JSP 2.0 for over another year.  If you're lucky enough to use
something like Resin, you'll probably have access to a 1.4 container in
the next month, but I people will have access to use this in the near
future.

> - the settters of your tag ahndler have to take an String as parameter, even 
> if the expression will be evaluated in another type (for instance, the value 
> attribute on <fmt:formatDate> is a java.util.Date)

Yes, I agree this is more work.  But more work programming your taglib
isn't necessarily a bad thing, especially if it is going to save you time
down the road by eliminating annoying and lengthy scriptlets.

> - your code will depend on Jakarta Taglib, not only JSTL/JSP classes

I'm not convinced this is necessary a bad thing because I've heard this
argument before.  If you wanted your implementation to depend on something
like Resin's evaluator, I could see this being a valid point.  However,
you implementation is always going to depend on something and I would feel
very confident on depending on the Jakarta implementation. One, it is
the reference implementation so you know that it completely follows the
JSTL specification.  Since JSTL is not part of J2EE 1.4, your going to be
depending on Jakarta if you want to use the tags anyways.  I very much
doubt that expression evaluation will differ between JSP 2.0 and JSTL, but
even if it does I would be willing to bet that the two will be keep in
synch.

-------------------
Eric Hauser
ehauser@indiana.edu
(317) 679-4766


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