[WordPress] A Helper Function for Admin Notices

00-display-admin-notice.php

<?php

/**
 * Provides an easy eay to display an administration notice based on the incoming
 * class and message.
 *
 * @param string $class   the class to add to the notice (warning, error, success)
 * @param string $message the message to display in the administration notice area
 */
protected function displayAdminNotice($class, $message)
{
    add_action(
        'admin_notices',
        function () use ($class, $message) {
            printf(
                '<div class="%1$s"><p>%2$s</p></div>',
                esc_attr($class),
                esc_html($message)
            );
        }
    );
}

01-admin-notice-error.php

<?php

if (!$this->hasValidInput()) {
    $this->displayAdminNotice(
        'notice notice-error',
        'You must specify a valid email address and license key.'
    );
}

02-admin-notice-success.php

<?php

if (update_option('acme-option', $values)) {
    $this->displayAdminNotice(
      'notice notice-success',
      'The options were updated successfully!'
  );
}

Couldn't find a comment box on the post itself. Great tip!

I think it would have been even better if you'd have internationalised the output?

@senlin

I have comments disabled on the blog, but you're on point with internationalization. I opt not to include it because it's out of scope of the content of the post but it's not something that should be ignored.

And it's something that I'm eventually going to cover more in-depth (though I have some resources already though it's a couple of years old).