gistfile1.txt

function melba_uc_init() {
  ...
  if ($_GET['q'] == 'cart' && !empty($_POST)) {
    // This is a continuation of a monstrosity born in 
    // sites/all/themes/melba/tempalates/views-view-table--cart-page.tpl.php
    $cart_id = uc_cart_get_id(FALSE);
    if (!empty($_POST['delete'])) {
      // delete items from cart
      foreach (array_keys(array_filter($_POST['delete'])) as $nid) {
        melba_uc_cart_item_remove($nid);
      }
    }
    if (!empty($_POST['qty'])) {
      // Update quantities for cart item
      foreach ($_POST['qty'] as $nid => $qty) {
        if (!is_numeric($qty)) {
          drupal_set_message(t('You must only enter a numeric figure in the quantity field.'), 'error');
          continue;
        }
        melba_uc_cart_item_qty($nid, $qty);
      }
    }
  }