function __construct()
 {
     maxCollections::checkExpireTrans();
     foreach ($this->uses_blocks as $block_name) {
         $block = maxCollections::getBlock($block_name);
         if ($block) {
             $block->setCollection($this);
             $block->set(array());
             // defaults
             $this->blocks[$block_name] = $block;
         }
     }
 }