Custom admin_notices Messages Ignored During Redirects

There are few things that I have pointed out in the code below too:

1. You were overwriting the options read from get_option using array_merge
2. You had hard-coded the Message Counts.
3. saving options in __destruct just does not work. (I don’t have any clue yet, may be experts will shed some light on it.

I have marked all the sections where I have made the changes with HKFIX, with a bit of description:

/**
 * Constructor
 * @author Ian Dunn <[email protected]>
 */
public function __construct()
{

    // Initialize variables
    $defaultOptions         = array( 'updates' => array(), 'errors' => array() );

    /* HKFIX: array_merge was overwriting the values read from get_option, 
     * moved $defaultOptions as first argument to array_merge */
    $this->options          = array_merge( $defaultOptions, get_option( self::PREFIX . 'options', array() ) );
    $this->updatedOptions   = false;

    /* HKFIX: the count for update and error messages was hardcoded,
     * which was ignoring the messages already in the options table read above
     * later in print the MessageCounts is used in loop
     * So I updated to set the count based on the options read from get_option */
    $this->userMessageCount = array();
    foreach ( $this->options as $msg_type => $msgs ) {
        $this->userMessageCount[$msg_type] = count( $msgs );
    }
    // more

    add_action( 'admin_notices',    array($this, 'printMessages') );
    add_action( 'post_updated',     array($this, 'saveCustomFields') );

    // does other stuff
}

/**
 * Saves values of the the custom post type's extra fields
 * @author Ian Dunn <[email protected]>
 */
public function saveCustomFields()
{
    // does stuff

    /* HKFIX: this was false, so changed it to true, may be not a fix but thought I should mention ;) */
    if( true )
        $this->enqueueMessage( 'foo', 'error' );

}

/**
 * Displays updates and errors
 * @author Ian Dunn <[email protected]>
 */
public function printMessages()
{

    foreach( array('updates', 'errors') as $type )
    {
        if( $this->options[$type] && ( self::DEBUG_MODE || $this->userMessageCount[$type] ) )
        {
            echo '<div id="message" class="'. ( $type == 'updates' ? 'updated' : 'error' ) .'">';
            foreach($this->options[$type] as $message)
                if( $message['mode'] == 'user' || self::DEBUG_MODE )
                    echo '<p>'. $message['message'] .'</p>';
            echo '</div>';

            $this->options[$type] = array();
            $this->updatedOptions = true;
            $this->userMessageCount[$type] = 0;

        }
    }

    /* HKFIX: Save the messages, can't wait for destruct */
    if ( $this->updatedOptions ) {
        $this->saveMessages();
    }

}

/**
 * Queues up a message to be displayed to the user
 * @author Ian Dunn <[email protected]>
 * @param string $message The text to show the user
 * @param string $type 'update' for a success or notification message, or 'error' for an error message
 * @param string $mode 'user' if it's intended for the user, or 'debug' if it's intended for the developer
 */
protected function enqueueMessage($message, $type="update", $mode="user")
{

    array_push($this->options[$type .'s'], array(
        'message' => $message,
        'type' => $type,
        'mode' => $mode
    ) );


    if($mode == 'user')
        $this->userMessageCount[$type . 's']++;

    /* HKFIX: save the messages, can't wait for destruct */
    $this->saveMessages();
}

/* HKFIX: Dedicated funciton to save messages 
 * Can also be called from destruct if that is really required */
public function saveMessages() 
{
        update_option(self::PREFIX . 'options', $this->options);
}

/**
 * Destructor
 * Writes options to the database
 * @author Ian Dunn <[email protected]>
 */
public function __destruct()
{
    /* HKFIX: Can't rely on saving options in destruct, this just does not work */
        // its very late to call update_options in destruct
        //update_option(self::PREFIX . 'options', $this->options);

}