[WordPress] Properly Writing WordPress Plugin Constructors

00-constructor-and-init.php

<?php

public function __construct( $data_manager ) {
	$this->data_manager = $data_manager;
}

public function init() {

	add_action(
		'hook_for_doing_something',
		array( $this, 'do_something' ),
		10, 1
	);
}