See comments below.
>>>>> "Jing" == Jing Zhou <[EMAIL PROTECTED]> writes:
>> Therefore, I would say that "<html-el:text>" (and similar tags) wouldn't
Jing> have a
>> "name" or "indexed" attribute. The "property" attribute (as I described
>> earlier) would be used both to get the current value and to specify the
Jing> request
>> parameter name. The current meaning of the "value" attribute should still
>> apply (overrides the property attribute for the current value).
Jing> There could be a way to enhance the current html tags while keeping the
Jing> semantics of "name", "property" which is one of beautiful things
Jing> in Craig's original thinking.
Jing> Suppose we define EL based name, property by attributes
Jing> _name, _property and initialize them to be null. Then we could have
Jing> protected String _name = null;
Jing> public void setName(String name) {
Jing> this._name = name;
Jing> }
Jing> protected String _property = null;
Jing> public void setProperty(String property) {
Jing> this._property = property;
Jing> }
Jing> public int doStartTag() throws JspException {
Jing> if (_name == null) {
Jing> name = Constants.BEAN_KEY; // so we do not need to initialize name
Jing> to be a non-null value any more
Jing> } else {
Jing> name = (String) ExpressionEvaluationManager.evaluate("name", _name,
Jing> String.class, this, pageContext);
Jing> if (name == null) {
Jing> name = Constants.BEAN_KEY;
Jing> }
Jing> }
Jing> if (_property == null) {
Jing> // throw new JspException("error message") or keep it depends on
Jing> particular tag implementations
Jing> } else {
Jing> property = (String) ExpressionEvaluationManager.evaluate("property",
Jing> _property, String.class, this, pageContext);
Jing> if (property == null) {
Jing> // some decisions here
Jing> }
Jing> }
Jing> ...
Jing> // make sure all RequestUtils.lookup will see only evaluated name,
Jing> property, scope
Jing> Object value = RequestUtils.lookup(pageContext, name, property, null);
Jing> }
Jing> Sometimes ago, I was trying to figure out if I could have a "compact"
Jing> attribute which
Jing> combine name/property/scope altogether when I design my UI. When I saw above
Jing> possibility, I feel it is not a good idea to combine them into one
Jing> attribute, because:
Jing> 1) The combined attribute could not provide enough additional power I could
Jing> buy:
Jing> End users could put a tag in multi-level loop like this:
Jing> <html-el:text name="some_name[${loop1Status.index}]"
Jing> property="p1[${loop2Status.index}].p2[${loop3Status.index}].p3" />
I guess you've partially lost me. Would the alternative for point (1) be:
<html-el:text
property="some_name[loop1Status.index].p1[loop2Status.index].p2[loop3Status.index].p3"/>
?
Which are you saying is preferable?
(Will the ActionForm processing successfully parse that "property" value so the
value can be set in the ActionForm?)
Jing> 2) If using combined attribute, I have to delemite the attribute into name,
Jing> property
Jing> again, which cost unnecessary CPU time and depend on end users correct
Jing> input.
Jing> I am very concerned about user experience: think about an UI for City,
Jing> State, Zip code,
Jing> How would you feel if a site give you only one text field to input the
Jing> city, state, and zip code? It will depend on the end users to input them in
Jing> correct
Jing> order with correct delimiters, it also need developers to parse the
Jing> attribute into
Jing> correct tokens. It will not be a good UI design.
Sorry, I don't understand. I'm not sure what you mean by "delemite the
attribute into name, property again". How does this depend on the end user's
correct input? Are you talking about the programmer, or the user of the
application?
Jing> So in general I hope the community could come out a design that keeps the
Jing> original
Jing> beauty of Struts and even the design could enhance the current html tags
Jing> without
Jing> having to create a "parallel" library in the end (Did someone say that
Jing> before?)
The only constant is change. There is movement towards using the JSTL. The
goal is to eventually have a Struts tag library that works cleanly with the
JSTL. This "parallel" library is only a transition strategy.
--
===================================================================
David M. Karr ; Java/J2EE/XML/Unix/C++
[EMAIL PROTECTED]
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