在class变量中存储一个类，我做得对吗？ PHP

Question

I am doing this currently,

class Page {
    // variable to hold DBC class
    public $dbc;
    /*
        __CONSTRUCT
        Called when class is initiated and sets the dbc variable to hold the DBC class.
    */
    public function __construct() {
        // set the dbc variable to hold the DBC class
        $this -> dbc = new DBC();
    }
    /*
        CREATE PAGE
        Create a page with the option to pass data into it.
    */
    public function create($title, $class, $data = false) {
        // start buffer
        ob_start('gz_handler');
        // content
        content($this -> dbc, $data);
        // end buffer and flush
        ob_end_flush();
    }

}

I have simplified the example, but basically I need to pass the object DBC to a function inside the method create?

Is this considered bad practice as I was using extends before but realised there was no way to extract the extended class to a variable?

Thanks

Answer 1

You're very close to the dependency injection design pattern.

You just have to change your constructor to accept the object as a parameter, like so:

public function __construct( $dbc) {
    // set the dbc variable to hold the DBC class
    $this -> dbc = $dbc;
}

Then instantiate your class with the database connection, like so:

$dbc = new DBC();
$page = new Page( $dbc);

This has a variety of benefits, ranging from easier to test, to making a single connection to the database. Imagine you need five Page objects - Now you pass them all the same database connection so they do not need to individually create one.