Nothing wrong with the other suggestions, but HTML::Template can do something similar:

//START
<tmpl_loop name="cases">
<tmpl_if name="__first__">
switch(x) {
</tmpl_if>
  case <tmpl_var name="case":
    // <tmpl_var name="case_code">
<tmpl_unless NAME="__last__">
       break;
<tmpl_else>   
}
</tmpl_unless>
//END
[download]

Loops have __first__, __last__, __inner__, __odd__ and __counter__.