Hey guys, this is not a big issue but I found an instance where the plugin shows an error if WP_DEBUG is enabled. Super easy to fix.
Notice: Undefined variable: groups in /Users/ungratefulbiped/Sites/dev.gv/wp-content/plugins/mailchimp/mailchimp.php on line 1221
It's caused by this code:
foreach ($_POST['group'][$ig['id']] as $i => $value) {
$groups .= str_replace(',', '\,', $value).',';
}
because you never initialize $groups and so the first .= makes PHP barf a little. All you have to do is add a line above with $groups = ''; and the problem is solved.
Do you normally test with WP_DEBUG enabled? It's really convenient for tracking issues and by making sure your plugin works with WP_DEBUG enabled you make your plugin more appealing to other WP developers who like to follow it as a standard.
http://codex.wordpress.org/Debugging_in_WordPress
Thanks