/**
* Checks if $this or any parent have an instance of $abstract class, and returns
* it if found, otherwise returns null.
*
* @param string $abstract
* @return object|null
*/
protected function getInstance($abstract)
{
// If an instance of the type is currently being managed as a singleton return it:
if (isset($this->instances[$abstract])) {
return $this->instances[$abstract];
}
// If not, try all parents:
if ($this->parent) {
return $this->parent->getInstance($abstract);
}
// Last parent will return null if none found it:
return null;
}
