I am contemplating building a code generator system, but I'm not sure on how to implement the code templates. I am preoccupied with simplicity of the syntax for the templates themselves (not necessarily for the associated perl code), to achieve some typical tasks.

So, this is a bit of a contest for templating systems, I am curious how you would implement one particular example problem, in your favourite templating system. The example problem is this: starting with a Perl array, it should produce the following output:

empty array: nothing is inserted

// BEGIN 
// END
[download]

one or more items: a global block is inserted (in this example, a switch statement, with braces), and for each item a subblock is inserted inside that global block (the individual cases). With the array = ("foo", "bar", "baz"), the desired output is:

// BEGIN
switch(x) {
  case foo:
    // code for foo
    break;
  case bar:
    // code for bar
    break;
  case baz:
    // code for baz
}  
// END
[download]

I'd like to point out one particularity, which often appears to be a weak spot. Note that there is no "break;" line after the last item in the list. The idea is that some particular text should be inserted between items in a loop, but not after the last item. It should act like the join string in join. As another example, it should be possible to expand a Perl array ("foo", "bar", "baz") into the text

    (foo, bar, baz)
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Thus, with commas between the items, but not at the end.

Again: at this point, I'm only interested in the templates themselves, and not yet in the Perl code to drive it.

To show what I am after, it could be something like the following, fictional example:

// BEGIN
<%IF @LIST%>
switch(x) {
<%FOREACH @LIST AS ITEM%>
  case $ITEM:
    // code for $ITEM
<%CONTINUE%>
    break;
<%/FOREACH%>
}
<%/IF%>
// END
[download]

So, if you know of a templating system that can do something like this: great! If you know of something better still... even better! :)

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