<?php
//create dependency injection container
class FileTypeA_DI_Container implements FileType_DI_Container{
  public function getFactory(){
    return new FileAFactory();
  }
}

//edit the ZipFile class to accept the DI container
class ZipFile{
  public function __construct(DI_Container $di){
    $this->di = $di;
  }

  //edit the readFiles method to make use of DI container?
  public function readFiles(){
    //loop
    $file = $this->di->getFactory()->createFile();
    //end loop
  }
}