uml-diagram-practice-1.php

<?php 

class MovieTheater {
    private $objectBoxOffice;
    private $objectMovie;

    public function __construct(BoxOffice $boxOffice)
    {
        // using composition
        $this->objectBoxOffice = $boxOffice;

        // using aggregation
        $this->objectMovie = new Movie;
    }
}

class BoxOffice {
    private $register;

    public function ticketDispenser() { /* */ }
    public function cashierMachine() { /* */ }
}

Class Movie {
    private $movie_name = 'Conan';
    private $rating;
    private $duration;

    public function playMovie() { /* */ }
}

// create a box office object
$boxOffice = new BoxOffice;

// create a movie theater object, passing the BoxOffice object as a property
$movieTheater = new MovieTheater($boxOffice);

// debugging
echo '<pre><code>';
print_r($movieTheater);

Notes

Modelling the UML diagram below into code. Only problem is that the private properties inside the Movie class are not accessible by the MovieTheater class. However, if we create a getter getMovieName() in the Movie class, then we could do $this->objectMovie->getMovieName(); and access the movie title.

Doing all this though, in my mind, seems to defeat the entire purpose of a private property. Not sure what conclusion to draw yet...

Print Array Dump

PHP considers both objects the same, what is different however is the way that the objects were instantiated - one through composition and the other through aggregation.

MovieTheater Object
(
    [objectBoxOffice:MovieTheater:private] => BoxOffice Object
        (
            [register:BoxOffice:private] => 
        )

    [objectMovie:MovieTheater:private] => Movie Object
        (
            [movie_name:Movie:private] => Conan
            [rating:Movie:private] => 
            [duration:Movie:private] => 
        )

)