gistfile1.php

<?php

// Using static methods
class Work {
	public function __construct() {
		// do work
	}
	public static function new_instance() {
		return new Work();
	}
}
add_action( 'admin_init', array( 'Work', 'new_instance' ) );

// Using Closures

add_action( 'admin_init', function() {
	// do work
} );