php对象继承

class foo
{
    public function printItem($string)
    {
        echo "Foo:".$string.PHP_EOL;
    }
    public function printPHP()
    {
        echo "PHP is great.".PHP_EOL;
    }
}
class bar extends foo
{
    public function printItem($string)
    {
        echo "Bar:".$string.PHP_EOL;
    }
}
$foo = new foo();
$bar = new bar();
$foo -> printItem('baz');
$foo -> printPHP();
$bar -> printItem('baz');
$bar -> printPHP();