[Webwork-devel] Adding i18n and text support to Velocity

[Bill B. <bi...@pr...>]

Hello,

I've been looking into the best way to add support for the equivalent of
the ww:i18n and ww:text JSP tags to Velocity.

One thing that seems apparent is that the ValueStack needs to be exposed
to Velocity templates in some manner.  This is at least true to get the
i18n functionality to work and may be necessary in other cases as well.

I'm planning on adding the ValueStack to the VelocityContext so it can be
accessed via the key $valuestack.  However, most usage will be wrapped in
macros like #pushvalue() and #popvalue() so users won't access $valuestack
directly.  For user visible methods such as findValue() and test(), I've
modified WebWorkUtil adding these methods to the delegate to the same
ValueStack methods.  This will allow these methods can be called using the
syntax $webwork.methodName().  In the case of findValue() that will
probably be available as $webwork.value(...).  

In the case of i18n support there would be an i18n macro that would be
called like this:
    #i18n("webwork.action.test.i18n.Shop")

By definition it would push the specified ResourceBundle on the ValueStack
thereby allowing the text support to use that ResourceBundle instead of
the default.  However, because this macro isn't a block tag, there needs
to be some way of popping the ResourceBundle off the ValueStack.  To do
this, I was going to expose the ValueStack popValue() method within a
macro:
    #popvalue()
Which would be implemented as $valuestack.popValue().

In like manner there are times when an Action or Bean needs to be pushed
onto the stack.  For instance:
    #action("i18n.Shop", $shop)
    #pushvalue($shop)
    ...
    #execute($shop)
    ...
    #popvalue()

I'm also looking into making an i18n block directive which would scope the
ResourceBundle instance as in:
    #i18n("webwork.action.test.i18n.Shop")
    ...
    #end

If I can get that to work, the popValue will be implied at the #end.

As far as support for text goes, I'm planning on adding a several text()
methods to WebWorkUtil.  As a result, they'll be available via the
$webwork context name.
    $webwork.text(key)
    $webwork.text(key, param0)
    etc.

In order to implement the parameter support, I'll copy the TextTag class
into the .velocity package and rework it with more appropriate API's for
Velocity.  After the 1.0 release, these two classes could be refactored so
they call a common class in .util.

Thanks for any feedback,
-Bill