GoF Flyweightパターン

Flyweight.php

<?php
class Item {
    private $code;
    private $name;
    private $price;
    
    public function __construct($code, $name, $price){
        $this->code = $code;
        $this->name = $name;
        $this->price = $price;
    }
    
    public function getCode(){
        return $this->code;
    }
    
    public function getName(){
        return $this->name;
    }
    
    public function getPrice(){
        return $this->price;
    }
}

class ItemFactory{
    private $pool;
    private static $instance = null;
    
    private function __construct($filename){
        //②buildPoolメソッド実行
        $this->buildPool($filename);
    }
    
    public static function getInstance($filename){
        if (is_null(self::$instance)){
            //①ItemFactoryをインスタンス化
            self::$instance = new ItemFactory($filename);
        }
        return self::$instance;
    }
    
    public function getItem($code){
        if (array_key_exists($code, $this->pool)){
            return $this->pool[$code];
        }else{
            return null;
        }
    }
    
    private function buildPool($filename){
        $this->pool = array();
        
        //ファイルを開いて行ごとにItemインスタンスを生成し、poolプロパティにセットする
        $fp = fopen($filename, 'r');
        while($buffer = fgets($fp, 4096)){
            var_dump(explode("\t", $buffer));
            list($item_code, $item_name, $price) = explode("\t", $buffer);
            $this->pool[$item_code] = new Item($item_code, $item_name, $price);
        }
        fclose($fp);
    }
    
    public final function __clone(){
        throw new RuntimeException('Clone is not allowed against ' . get_class($this));
    }
}

function dumpData($items){
    echo "<dl>";
    foreach($items as $item){
        echo "<dt>" . $item->getName() . "</dt>";
        echo "<dd>" . $item->getCode() . "</dd>";
        echo "<dd>" . $item->getPrice() . "</dd>";
    }
    echo "</dl>";
}

$factory = ItemFactory::getInstance('data.txt');

$items = array();
$items[] = $factory->getItem('ABC0001');
$items[] = $factory->getItem('ABC0002');
$items[] = $factory->getItem('ABC0003');

dumpData($items);