Costin,
>
> On Fri, 21 Jun 2002, Kin-Man Chung wrote:
>
> > Use of scripting varibles in nested tag never work before, so obviously
> > no body uses it much. I think the whole scripting variable in JSP1.2 is
> > poorly designed, and not well understood.
>
> The failures are from an app that worked perfectly fine with
> jasper1, and with jasper2 ( up to 4.1.4 ).
>
> And IMHO are very elementary use cases - 2 iterates and one
> condition is not that infrequent.
>
jasper1 and old jasper2 implements scripting variables by declaring them
when a tag handler is instantiated, inside a block of its own, like
{
String x; // variable x defined here
...
}
This implementation has 2 problems.
1) Nested tags with same variable does not work
<mytag:foo>
<mytag:foo>
</mytag:foo>
</mytag:foo>
because you cannot have two varibles of the same name in Java, even if
they are in blocks nested within one another.
2) The variables are out of scope when the tag ends, but for variables
with AT_BEGIN scope, spec says they should be accessable until the
end of the page.
>
> > > How do we deal with nested tags of different type ? I don't have
> > > a test case, but I assume someone may have a NESTED tag
> > > 'foo' in 2 different tags, with different declared types ( String and
> > > Integer ). The current generator seems to not create { },
> > > and I'm not sure how this will work.
> > >
> > > ( no test case - but I'm sure you can find such tags )
> > >
> >
> > That would not work, and would never be made to work, not only for
> > nested case, but also for non-nested tags with AT_BEGIN scopes.
> > I tend to think this falls into the user's reponsibility if she uses
> > the same variable name for two different types, somewhat analogous to
> > declaring two variables of the same name two different types in Java.
>
> I'm lost here - wasn't NESTED supposed to define a lexical scoping ?
> I don't see why this wouldn't work - are you saying it doesn't
> work with jasper2, it didn't worked with jasper1, or is not
> required by the spec ?
>
You cannot have
{
String x;
{
String x;
}
}
in Java, so we are implementing scripting variables with nested scopes as
{
String x;
{
String temp = x;
...
}
x = temp;
}
You can see why we'll have problems if two variables nesting with one
anothers have the same name but different types.
>
> > Hopefully, there won't be a need for scripting variables anymore when
> > expression language becomes available in JSP2.0.
>
> :-)
>
> Unfortunately JSP1.x will be around for a while, and jasper must support
> it.
>
> Costin
>
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