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https://issues.apache.org/jira/browse/VELOCITY-704?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12676037#action_12676037
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Nathan Bubna commented on VELOCITY-704:
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Ok, #stop is now a directive that takes an optional Scope argument and #break
uses StopCommand.
I've also been thinking more about $global, and i think it's unnecessary. In
the 1.x trunk, there is already no means for setting a global variable if
velocimacro.context.localscope is turned on. So, there's no backward
compatibility issue in not having it. And it wouldn't make sense to add it,
since i'll be removing velocimacro.context.localscope in 2.0. We just need to
actively deprecate velocimacro.context.localscope and encourage/warn those who
use it to switch to using the $macro namespace when they want to keep a macro
var locally scoped.
In regard to deprecating the replaced features, here's my thoughts for 1.x:
- Deprecate velocimacro.context.localscope by warning users who set it to true
in the logs that they should use $macro instead.
- Deprecate #break and put a notice in the logs that users should use
#stop($foreach) instead.
- When users have non-default velocityCount or velocityHasNext settings, warn
them in the logs that they should switch to $foreach.count and $foreach.hasNext
- Update all the documentation to refer only to the new stuff.
- Leave these things as such for the remainder of 1.x's lifetime. Only
actually remove them in 2.0.
> VTL Simplicity - "Control" objects
> ----------------------------------
>
> Key: VELOCITY-704
> URL: https://issues.apache.org/jira/browse/VELOCITY-704
> Project: Velocity
> Issue Type: New Feature
> Components: Engine
> Reporter: Nathan Bubna
> Assignee: Nathan Bubna
> Fix For: 2.0
>
>
> In the discussion for VELOCITY-680, Claude suggested the addition of what i'm
> calling "control" objects as a solution. These would have the same name as
> the block directive or macro to which they belong. At a minimum, these
> would provide get(key), set(key, value) and stop() methods to control the
> reference scoping and execution of the block to which they belong.
> Directives could extend the basic control object to provide additional
> functions, such as index() and hasNext() for #foreach. Here's some examples:
> #foreach( $user in $users )
> $user#if( $foreach.hasNext ), #end
> #if( $foreach.count > 10 ) $foreach.stop() #end
> #end
> #macro( foo $bar )
> blah blah #if( $bar == 'bar' ) $foo.stop() #end
> #set( $foo.woogie = 'woogie' )
> $foo.woogie
> #end
> #foreach( $item in $list )
> #set( $outer = $foreach )
> #foreach( $attr in $item.attributes )
> #if ( $attr == $null ) $outer.stop()#end
> #end
> #end
> ------foo.vm---------
> blah blah $template.stop() blah
> ------------------------
> #define( $foo )
> blah blah $define.stop() blah
> #end
> This could allow us to greatly simplify all sorts of things. We could remove
> the #break, #stop and #return directives. We would no longer need to have
> "local" contexts for foreach loops or macros; instead users could set and get
> local variables directly in the provided namespace. All else would be
> global. This may even cut down our internal code complexity a fair bit.
> It'll certainly obviate the need for several configuration properties and
> internal contexts. Everything becomes much more explicit, obvious and
> robust. I also don't think it looks ugly. :)
> We would, of course, have to make sure that the StopExceptions thrown by
> stop() aren't wrapped into MethodInvocationExceptions. We'd have to make the
> directives clean up their control when done rendering, and if they're nested
> in a directive of the same type, then they should save and restore the
> reference to the parent control. We'd also have to figure out a good
> default name to give the control objects for the top-level control object,
> and whether it would be different than the name of the control object used
> during a #parse call. $template? $parse? $velocity? If we wanted to use
> $template--which i think works well for both top-level and #parse--then we'd
> probably have to make it configurable, since that's likely to conflict. And
> if we make that configurable, i suppose we may as well make it configurable
> for the others too.
> I'm struggling to think of any real downside to this. Most of the replaced
> features (implicit macro localscope, #stop, #break, $velocityHasNext) are
> either not default behavior or are new features. I'd wager that most people
> would only have to change $velocityCount to $foreach.count. Even that's no
> big deal, since this would be for a major version change. , The worst i can
> think of is the fact that for a couple of these controls it would mean a few
> more keystrokes. Considering all the gains in extensibility, explicitness
> and simplification (for us and users), i think it's worth a few keystrokes.
> What do you guys think?
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