WordPress Complete - Sixth Edition

Adding messages

Whenever a user updates, previews, or does anything with a book, you'll want them to see an accurate message. All we need to do is create an array of messages and then hook them to WordPress. Here's the code for doing that:

function book_updated_messages( $messages ) { 
  $messages['book'] = array( 
    '', /* Unused. Messages start at index 1. */  
    sprintf('Book updated. <a href="%s">View book</a>',     esc_url(get_permalink($post_ID))),  
    'Custom field updated.',  
    'Custom field deleted.',  
    'Book updated.',  
    (isset($_GET['revision']) ?     sprintf('Book restored to revision from %s',     wp_post_revision_title((int)$_GET['revision'], false)) : false), 
    print('Book published. <a href="%s">View book</a>',  esc_url(get_permalink($post_ID))), 'Book saved.', ...