【PHP】parent - スーパークラスのメソッド呼び出し

<?php

// 人間クラス
class Person {
    
    public function greeting() {
        echo "Hey!\n";
    }
    
}

// 教師クラス
class Teacher extends Person {
    
    public function greeting() {
        ___ih_hl_start
        parent::greeting();
        ___ih_hl_end
        echo "I'm a teacher.\n";
    }
    
}

$teacher = new Teacher();

$teacher->greeting();

?>

$ php sample.php
Hey!
I'm a teacher.

<?php

// 人間クラス
class Person {
    
    // 名前
    public $name;
    
    // コンストラクタ
    public function __construct( $name ) {
        $this->name = $name;
    }
    
    // あいさつ
    public function greeting() {
        echo "Hey!\n";
        echo "My name is ". $this->name . ".\n";
    }
    
}

// 教師クラス
class Teacher extends Person {
    
    // 担当科目
    public $subject;
    
    // コンストラクタ
    public function __construct( $name, $subject ) {
        ___ih_hl_start
        parent::__construct($name);
        ___ih_hl_end
        $this->subject = $subject;
    }
    
    // あいさつ
    public function greeting() {
        echo "Hello.\n";
        echo "I'm a " . $this->name . ", a " . $this->subject . " instructor.\n";
    }
    
}

$teacher = new Teacher('TANAKA', 'Programming');

$teacher->greeting();

?>

$ php sample.php
Hello.
I'm a TANAKA, a Programming instructor.