Delegation

Delegation.php

<?php

class OfficeDelegation implement BackupPowerDelegateInteface, PrinterDelegateInterface
{

   public function duringOfficeLogic()
   {
      if($this->powerIsOff()){
        $backupPower = new BackupPowerHandler();
        $backupPower->setDelegate($this);
	    }
   }

   public function successTurnonPowerBackup()
   {
	    $this->turnOnPrinter();
   }

   /**
    * Implement delegation handler for BackupPowerDelegateInteface 
    */
   public function errorTurnonPowerBackup()
   {
	    //Doing something on failure
   }

   /**
    * Implement delegation handler for BackupPowerDelegateInteface 
    * @var DocumentInterface[]
    */
   public function finishedPrintDocuments($documents)
   {
	    //Doing something on failure
   }
}