一天一个设计模式（16）——备忘录模式

备忘录模式

<?php
class Memento{
    private $_state;
    public function __construct($state){
        $this->_state=$state;
    }

    public function getState(){
        return $this->_state;
    }
}

class MementoManager{
    private $_mementoList=[];
    public function add($memento){
$this->_mementoList[]=$memento;
    }
    public function get($index){
return $this->_mementoList[$index];
    }
}

class Demo{
    public $state;
    public function save(){
        return new Memento($this->state);
    }

    public function get($memento){
return $memento->getState();
    }

    public function set($memento){
        $this->state=$memento->getState();
    }
}

$demo=new Demo();
$manager=new MementoManager();

$demo->state='state1';
$manager->add($demo->save());

$demo->state='state2';
$demo->state='state3';
$manager->add($demo->save());

$demo->state='state4';
echo $demo->state.PHP_EOL;

$demo->set($manager->get(1));
echo $demo->state.PHP_EOL;

$demo->set($manager->get(0));
echo $demo->state.PHP_EOL;