Adapterパターン

adapter.php

<?php

//既存のクラス
class Banner {

    private $string;

    public function __construct($text) {
        if (is_string($text)) {
            $this->string = $text;
        } else {
            die;
        }
    }

    public function showWithParen() {
        echo '(' . $this->string . ')';
    }

    public function showWithAster() {
        echo '*' . $this->string . '*';
    }

}

//必要とされているインターフェース
interface MyPrint {

    public function printWeak();

    public function printStrong();
}

//変換クラス
class PrintBanner extends Banner implements MyPrint {

    public function __construct($text) {
        parent::__construct($text);
    }

    public function printWeak() {
        parent::showWithParen();
    }

    public function printStrong() {
        parent::showWithAster();
    }

}

//main
function writeWithPrint(MyPrint $print) {
    $print->printStrong();
    $print->printWeak();
}

$printer = new PrintBanner('hello world');
writeWithPrint($printer);