public function visitBook(Book $book)
{
$price = $book->getPrice();
// implement $5 discount
if ($price > 20) {
$price -= 5;
}
return $price;
}
public function testVisitor()
{
$visitor = new PriceItemVisitor();
$item = new BookItem($name = "Im Westen nichts Neues, Erich Maria Remarque", $price = 22.5);
$price = $item->accept($visitor);
$this->assertEquals(17.5, $price);
$item = new FruitItem($name = "apple", $pricePerKg = 1.5, $weight = 2);
$price = $item->accept($visitor);
$this->assertEquals(3.0, $price);
}