Login and Registration: Add expiration support for dismissing notices.

[costdev]

This adds support for an array dismissible value in wp_get_admin_notice().

The array:

array(
    // (string) Required. Cannot be empty.
    'slug'       => 'mynotice',
    // (int) Optional. Seconds to dismiss for. Must be >= 0. Default 0 (permanently dismissed).
    'expiration' => 60,
)

Examples

Make a notice permanently dismissible

wp_get_admin_notice(
    __( 'A notice that will be dismissed permanently.' ),
   array(
       'type'        => 'info',
       'dismissible' => array( 'slug' => 'mynotice' ),
   )
);

Make a notice dismissible for 30 days

wp_get_admin_notice(
    __( 'A notice that will be dismissed for 30 days.' ),
    array(
        'type'        => 'info',
        'dismissible' => array(
            'slug'       => 'mynotice',
            'expiration' => 30 * DAY_IN_SECONDS,
        ),
    )
);

Make all notices permanently dismissible

add_filter( 'wp_admin_notice_args', 'dismiss_each_admin_notice_permanently', 10, 2 );
function dismiss_each_admin_notice_permanently( $args, $message ) {
    $args['dismissible'] = array(
        'slug'       => md5( $message ), // So its transient is unique to that message.
    );
    return $args;
}

Make all notices dismissible for 30 days

add_filter( 'wp_admin_notice_args', 'dismiss_each_admin_notice_for_30_days', 10, 2 );
function dismiss_each_admin_notice_for_30_days( $args, $message ) {
    $args['dismissible'] = array(
        'slug'       => md5( $message ), // So its transient is unique to that message.
        'expiration' => 30 * DAY_IN_SECONDS,
    );
    return $args;
}

Trac ticket: