/**
  * Adds an object to the instance pool.
  *
  * Propel keeps cached copies of objects in an instance pool when they are retrieved
  * from the database.  In some cases -- especially when you override doSelect*()
  * methods in your stub classes -- you may need to explicitly add objects
  * to the cache in order to ensure that the same objects are always returned by doSelect*()
  * and retrieveByPK*() calls.
  *
  * @param      CourseField $value A CourseField object.
  * @param      string $key (optional) key to use for instance map (for performance boost if key was already calculated externally).
  */
 public static function addInstanceToPool(CourseField $obj, $key = null)
 {
     if (Propel::isInstancePoolingEnabled()) {
         if ($key === null) {
             $key = (string) $obj->getId();
         }
         // if key === null
         self::$instances[$key] = $obj;
     }
 }
 /**
  * Exclude object from result
  *
  * @param     CourseField $courseField Object to remove from the list of results
  *
  * @return    CourseFieldQuery The current query, for fluid interface
  */
 public function prune($courseField = null)
 {
     if ($courseField) {
         $this->addUsingAlias(CourseFieldPeer::ID, $courseField->getId(), Criteria::NOT_EQUAL);
     }
     return $this;
 }