laravelIoc.php

<?php
interface sessionStorage{
  public function get($key);
  public function set($key,$value);
}
class fileSessionStorage implements sessionStorage {
  public function get($key){
    ...
  }
  public function set($key,$value){
    ...
  }
}
class mysqlSessionStorage implements sessionStorage {
  public function get($key){
    ...
  }
  public function set($key,$value){
    ...
  }
}
class userClass {
  protected $session;
  public function __construct(sessionStorage $session){
    $this->session = $session;
  }
}
App::bind('sessionStorage','mysqlSessionStorage');