The loop directive includes two built-in variables that you can use for embedded if conditions. The variables are: _length and _index. The _length variable evaluates to the length of the arrays processed by the loop directive, while the _index variable evaluates to the current index of the 'loop' directive. To ensure that the variables are only recognized as directives, and not as actual parameters to be passed into the loop, do not enclose either variable in @@’s.

An example of using built-in variables is to apply them to the import attribute of the page directive. The import attribute requires comma separation of packages. If the loop directive extends around the entire import attribute, you would only output the attribute name import= on the first iteration of the loop--this includes the closing double quote (")--and not output a comma on the last iteration of the loop. Using the built-in variable, you can express this as follows:

<@loop (@@Import@@)@>
<@ if(_index == 0)@>import="
<@endif@>@@Import@@<@if (_index == _length-1)@>"<@else@>,
<@ endif @>
<@endloop@>