This 来自WordPress网站，我在文档中找不到我的答案。当我发布register_post_type, 它如何知道要使用哪个函数？我知道init 已使用自定义挂钩填充操作codex_book_init, 但当我看register\\u post\\u类型时。它只有“书”：

add_action( \'init\', \'codex_book_init\' );

register_post_type( \'book\', $args );

add_action( \'init\', \'codex_book_init\' );
/**
 * Register a book post type.
 *
 * @link http://codex.wordpress.org/Function_Reference/register_post_type
 */
function codex_book_init() {
    $labels = array(
        \'name\'               => _x( \'Books\', \'post type general name\', \'your-plugin-textdomain\' ),
        \'singular_name\'      => _x( \'Book\', \'post type singular name\', \'your-plugin-textdomain\' ),
        \'menu_name\'          => _x( \'Books\', \'admin menu\', \'your-plugin-textdomain\' ),
        \'name_admin_bar\'     => _x( \'Book\', \'add new on admin bar\', \'your-plugin-textdomain\' ),
        \'add_new\'            => _x( \'Add New\', \'book\', \'your-plugin-textdomain\' ),
        \'add_new_item\'       => __( \'Add New Book\', \'your-plugin-textdomain\' ),
        \'new_item\'           => __( \'New Book\', \'your-plugin-textdomain\' ),
        \'edit_item\'          => __( \'Edit Book\', \'your-plugin-textdomain\' ),
        \'view_item\'          => __( \'View Book\', \'your-plugin-textdomain\' ),
        \'all_items\'          => __( \'All Books\', \'your-plugin-textdomain\' ),
        \'search_items\'       => __( \'Search Books\', \'your-plugin-textdomain\' ),
        \'parent_item_colon\'  => __( \'Parent Books:\', \'your-plugin-textdomain\' ),
        \'not_found\'          => __( \'No books found.\', \'your-plugin-textdomain\' ),
        \'not_found_in_trash\' => __( \'No books found in Trash.\', \'your-plugin-textdomain\' )
    );

    $args = array(
        \'labels\'             => $labels,
        \'public\'             => true,
        \'publicly_queryable\' => true,
        \'show_ui\'            => true,
        \'show_in_menu\'       => true,
        \'query_var\'          => true,
        \'rewrite\'            => array( \'slug\' => \'book\' ),
        \'capability_type\'    => \'post\',
        \'has_archive\'        => true,
        \'hierarchical\'       => false,
        \'menu_position\'      => null,
        \'supports\'           => array( \'title\', \'editor\', \'author\', \'thumbnail\', \'excerpt\', \'comments\' )
    );

    register_post_type( \'book\', $args );
}