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From Shawn Bayern <>
Subject Re: Proposal: JSP/JSTL expression language
Date Fri, 19 Jul 2002 01:30:30 GMT
Various responses --

On Thu, 18 Jul 2002, Craig R. McClanahan wrote:

> I would imagine that we'll have a set of unit tests in this
> repository, just as we do for the other commons packages.  It might be
> possible to adopt some sort of "here's a set of expressions and
> expected values" things as part of that, which could be used for
> testing multiple expression language implementations as part of this.

We actually have something like this already, which I'd plan on migrating
over too.  It's a set of positive and negative regression tests for
parsing, and a (limited) framework for testing evaluation.  Some tests
will need to be reworked to accommodate both a JSP 1.0 and JSP 2.0

On Thu, 18 Jul 2002, Jeff Turner wrote:

> +1
> Though I'm not sure about the name 'el', because what with jexl and
> jxpath, it certainly isn't the only "expression language" at Jakarta.

Indeed.  I never intend this, but everything I name somehow ends up with
the most generic name possible.  (JSTL's implementation at Jakarta is
called, as a product name, the "Standard Taglib."  The centralized
authentication and single sign-on system I wrote for Yale is called the
"Central Authentication Service."  And so forth.)  :-)

So I'm all for a better name.  James Strachan suggested "JEL," but that
might be confusing against Jelly.  It's unfortunate that "Espresso" is
taken, since it's apt. It might be cute to name it after a salient
syntactic feature, like "Dot."  Any better ideas?

On Fri, 19 Jul 2002, Geir Magnusson Jr. wrote:

> I am all for JSTL becoming a Commons component if Jexl can as well.  
> If JSTL rules out other competing implementations, I'm -1

Don't see any reason they should be exclusive.  I'm actually quite pleased
that Jexl exists so that the "compliant" EL doesn't become too much of a
playground for new features.  On the other hand, like I said, I'm not
adverse to having a mode for the EL whereby extra, non-JSP features are
added; in fact, this might be necessary to support Faces and other clients
of the EL.

(By the way, just to get into some specifics, I'm envisioning an interface
along the lines of some factory that lets you return an instance of
"Evaluator" -- the generic hanger for methods to validate and evaluate
expressions -- appropriate to the standard (or custom product) you're
looking for.  So you could say, "Give me a JSTL 1.0 expression
interpreter," "Give me the latest version of the JSP expression
interpreter," and so forth.)

Shawn Bayern
"JSTL in Action"

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