Drupal 7 – Dynamic select options for Webform

<?php
function webform_options_webform_select_options_info() {

    // get all content types
    $node_types = array_keys(node_type_get_names());

    $items = array();
    // for each of the content types, create an item
    foreach($node_types as $ntype){
        // returns function names as lambda_1, lambda_2, ...
        $callback_func = create_function('', 'return _get_node_titles("'.$ntype.'");');
        $items[$ntype] = array(
            'title' => t('Node: ' . $ntype),
            'options callback' => $callback_func,
        );
    } // foreach
    return $items;

} // webform_options_webform_select_options_info()

function _get_node_titles($node_type) {

    $options = array();
    $sql = "SELECT nid, title FROM {node} WHERE type = '$node_type'";
    $result = db_query($sql);
    foreach ($result as $row) {
        $options[$row->nid] = $row->title;
    }
    return $options;
} // _get_node_titles()