Make node listings more themeable

A friend of mine ran into this issue a while ago: Node listings like on the frontpage or for categories are not really themeable. The nodes themselves are, of course, but the list is not.

This makes it - at least - very hard, if you want for exampel surround all sticky nodes with a single div for design reasons. Or if want your node list to be a definition list, rather than a set of divs. Or...

Additionally, since a theme function is missing, there is a lot of duplicated code around Drupal modules that usually looks like this:

    $output = '';
    while ($node = db_fetch_object($result)) {
      $output .= node_view(node_load($node->nid), 1);
    }

Grep for "node_view(node_load(" on the sources to find all the occurences.

I therefore suggest to add a function theme_node_listing to node.module (the name "theme_node_list" is already occupied) to contain this code:

function theme_node_listing($result) {
  $output = '';
  while ($node = db_fetch_object($result)) {
    $output .= node_view(node_load($node->nid), 1);
  }
  return $output;
}

Note that the function takes a database result as argument.

The code mentioned above then can be replaced by

$output = theme('node_listing', $result);

Having centralized node listing formatting this way, the original problem of surrounding sticky nodes with a div can be solved by simply overloading the theme function in the theme engine of choice.