不要将函数用于回调，请使用类。类似这样：

class Competition_Manager_Page
{
    private $extra;

    public function set_extra( $value )
    {
        $this->extra = $value;
    }

    public function render()
    {
        // show you page content, then:
        print $this->extra;
    }
}

现在，注册菜单时，首先创建该类的实例，然后添加额外数据：

$page = new Competition_Manager_Page;
$page->set_extra( \'Test\' );

add_menu_page(
    \'Competition Manager 2013-2014\',
    \'2013-2014\',
    \'manage_options\',
    \'manager_2013_2014\',
    array( $page, \'render\' ), // replacement for the former function
    plugins_url( \'competition-manager/images/cup.png\' ), 81
);