<?php
class Show_message {
    public $message_instance = ""; //ensure Message object variable is visible
    function __construct() {
        $this->message_instance = new Message();
    }
    function display_message() {
         //instatiate Message object
        echo $this->message_instance->message . " : in display_message function <br>"; //works
    }
    function display_again() {
        echo $this->message_instance->message . " : in display_again function <br>"; //does not work
    }
}
class Message {
    public $message = ""; //ensure $this->message variable is visible?
    function __construct() {
        $this->message = "Hello world"; //make message
    }
}
$instance = new Show_message(); //instatiate Show_message object
$instance->display_message(); //method to create instance and display message
$instance->display_again(); //method to display message again
?>

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