I write the code according to the lessons, why the error?

Question

Yii

The actual code

public $name;
  public $email;
  public $text;

  public function attributeLabels() {
    return[
      'name'=>"Имя",
      'email'=>"E-mail",
      'text'=>"Текст сообщения",
    ];
  }
  public function rules() {
    return[
      [['name','email']=>'required'] //ERROR  Illegal offset type
    ];
  }

Answer 1

Because you can't use an array as an array key.