Closures for Pipp

In the last days I have been working on supporting closures for Pipp. Yes, you’ve read correctly. The next version of PHP will support real closures. See http://www.ibm.com/developerworks/opensource/library/os-php-5.3new2/index.html?ca=drs-tp5008 for a nice writeup.

Closures are connected with lexical variables, so I had I had to rethink the way I handle variables in Pipp. Initially I had the variables outside functions as package variables. Since this doesn’t play well with closures, and as there are problems with included files, I changed those to lexical variables. This was the major part of the work. Thanks to Patrich Michaud for advising me where I should define the lexicals.

After switching to lexicals everywhere I followed my usual approach and tried to do the same as Rakudo does. This worked without hassle for a simple case.

<?php

  function gen_indentor ( ) {
      $indention = '+';
      $indentor = function ($line) use ($indention) {
          echo $indention . $line . "\n";
      };

      return $indentor;
  }

  $sub_1 = gen_indentor();

  $sub_1('one plus');

?>

correctly gives:

+one plus

But when I create a second closure I run into problems.

<?php

  function gen_indentor ($indention) {
      $indentor = function ($line) use ($indention) {
          echo $indention . $line . "\n";
      };

      return $indentor;
  }

  $sub_1 = gen_indentor('+');
  $sub_4 = gen_indentor('++++');

  $sub_1('one plus');
  $sub_2('four plusses');

?>

incorrectly gives:

++++one plus
++++four plusses

Looks like I need to fiddle some more.