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https://issues.apache.org/jira/browse/VELOCITY-600?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12603690#action_12603690
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Nathan Bubna commented on VELOCITY-600:
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I'm not at all opposed to $velocityHasNext. I was just offering my preferred
solution. For me, the object creation and extra calls are negligible and which
"looks better" is entirely subjective. You and i, at least, seem to have
different opinions. ;) I also generally use the shorthand $loop.last and like
that i can have $loop.first, $loop.last, $loop.index, $loop.count, and other
interesting features available when i want them, with no cost if i don't use
them. And since Tools 2 lazy loads tools, $loop itself also costs nothing
until i use it.
But really, $velocityHasNext sounds fine and cheap to me. Care to turn your
code above into a patch for easy application? :)
> #foreach & velocityCount
> ------------------------
>
> Key: VELOCITY-600
> URL: https://issues.apache.org/jira/browse/VELOCITY-600
> Project: Velocity
> Issue Type: Improvement
> Components: Engine
> Reporter: Adrian Tarau
> Priority: Minor
> Fix For: 1.5.1
>
>
> velocityCount = Used in the #foreach() directive, defines the string to be
> used as the context key for the loop count. A template would access the loop
> count as $velocityCount.
> Knowing current version of the loop counter is very useful, but something is
> missing. Very often, when you generate some content base on a
> model(JavaScript code based on some UI model) you have the need to know if
> this is the last time when the #foreach block will be executed or not.
> Example
> You have a collection of objects Property(bean with key, value fields) and
> you want to generate a JavaScript object with them. The result should be like
> this :
> {id : 1 , name = "John", ...}
> you can generate this with
> {
> #foreach($property in $properties)
> $property.key : "$property.value" #if($velocityCount !=
> $properties.size()) , #end
> #end
> }
> You can store $properties.size() of course outside the loop.
> The template will be less verbose if I will have something like that.
> #if($velocityHasNext) , #end.
> Instead of saving only the counter, a new variable called velocityHasNext
> whould be populated with the result of iterator.hasNext(). This is a minor
> modification of current #foreach directive
> while (!maxNbrLoopsExceeded && i.hasNext())
> {
> // TODO: JDK 1.4+ -> valueOf()
> context.localPut(counterName , new Integer(counter));
> context.localPut(hasNextName , i.hasNext()); <--- here is the
> change
> Object value = i.next();
> context.localPut(elementKey, value);
> /*
> * If the value is null, use the special null holder context
> */
> if( value == null )
> {
> if( nullHolderContext == null )
> {
> // lazy instantiation
> nullHolderContext = new NullHolderContext(elementKey,
> context);
> }
> node.jjtGetChild(3).render(nullHolderContext, writer);
> }
> else
> {
> node.jjtGetChild(3).render(context, writer);
> }
> counter++;
> // Determine whether we're allowed to continue looping.
> // ASSUMPTION: counterInitialValue is not negative!
> maxNbrLoopsExceeded = (counter - counterInitialValue) >=
> maxNbrLoops;
> }
> also init should contain
> public void init(RuntimeServices rs, InternalContextAdapter context, Node
> node)
> throws TemplateInitException
> {
> super.init(rs, context, node);
> counterName = rsvc.getString(RuntimeConstants.COUNTER_NAME);
> hasNextName = rsvc.getString(RuntimeConstants.HAS_NEXT_NAME);
> counterInitialValue =
> rsvc.getInt(RuntimeConstants.COUNTER_INITIAL_VALUE);
> ....
> }
> This should help creating clear templates(and avoid some mistakes, sometime -
> like using the wrong collection to test :) ).
> Thanks.
>
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