gistfile1.txt

add_filter('pre_comment_content', 'encode_code_in_comment');

function encode_code_in_comment($source) {
  $encoded = preg_replace_callback('/<code>(.*?)<\/code>/ims',
  create_function(
    '$matches',
    '$matches[1] = preg_replace(
        array("/^[\r|\n]+/i", "/[\r|\n]+$/i"), "",
        $matches[1]);
      return "<code>" . esc_html( $matches[1] ) . "</code>";'
  ),
  $source);

  if ($encoded)
    return $encoded;
  else
    return $source;
}