The instructions in the article are for plugin developers, to make their own notices dismissible. The plugin you suggest would be very different and I believe many such plugins exist. After a quick google search it seems you are looking for something like WordPress Notification Manager?

running a multisite it is very annoying.

You are correct in that this is a good improvement.

As for transients, I would like to use them in theory, but I’ve found many times that they do not operate as expected in actual people’s installations. Haven’t dug deep into this though. If they work for you, then great.

Thank you very much for sharing your code!

Thank you, I’m glad you found it useful! 🙂

Agree, and thanks for the article 🙂

I’ve been through this and a couple of things I’d tweak (personally).

You have this line

myplugin_dismissed_{$admin_notice->dismiss_option}

which will always save myplugin_dismissed_1 so if I want to do various notices throughout my plugin dismissing one seems to dismiss them all

why not do:-

myplugin_dismissed_{$admin_notice->dismiss_name}

passing

$this->notice( ‘error’, $message, $dismiss_option, $dismiss_name );

I’ve also tweaked it to give the option of set_transient for dismissible notices which return after a set period 🙂

Put my tweaks here: https://pastebin.com/JJSrmdrH

Yes this is one feature that should eventually go into core I think.

You call the function as

$notices = MyPlugin_Admin_Notices::get_instance();
$notices->error( 'something broke', 'user-knows-something-broke' );

Of course it will not work if you call it after the admin_notices action fires.

Would be nice to see this article show how one would make an admin notice appear using the class.