php 定义protect变量

class BaseClass {
    protected $protectedVar = 'I am protected';

    protected function protectedMethod() {
        return 'This is a protected method';
    }
}

class SubClass extends BaseClass {
    public function accessProtected() {
        // 子类可以访问父类的 protected 成员
        return $this->protectedVar . ' and ' . $this->protectedMethod();
    }
}

$subClassInstance = new SubClass();
echo $subClassInstance->accessProtected(); // 输出: I am protected and This is a protected method

class SubClass extends BaseClass {
    protected function protectedMethod() {
        return 'This is an overridden protected method';
    }
}

$subClassInstance = new SubClass();
echo $subClassInstance->accessProtected(); // 输出: I am protected and This is an overridden protected method