Be careful about duplicating events

Ever since Laravel introduced automatic event discovery, I've still preferred to manually register my events and listeners.

Events and listeners already tend to be a little bit "hidden" in an app, but at least with manual registration in the EventServiceProvider, you have one place to look to see what's going on at a high level.

In Laravel 11, as part of the "slimming" to one service provider, another change was introduced which turned event discovery on by default. More significantly, this new default comes into effect even if you don't slim your Laravel 10 app, leaving the EventServiceProvider in place.

Why is this a problem?

With the new default on top of my manual wiring, an event gets registered to the same listener twice: once from my manual wiring, and another time from the discovery which relies on the parameter type-hint in my listener. This means the code in those listeners actually runs twice. Definitely not good!

I don't see it mentioned in the docs, but you can still alter this new default behavior:

// app/Providers/EventServiceProvider.php
public function boot()
{
    static::disableEventDiscovery();
}

With that one line change, we were no longer accidentally running the listeners twice.

Here to help,

Joel

P.S. At the beginning of the original Zelda game, Link gets a sword from a guy who says "It's dangerous to go alone! Take this." That's a good metaphor for software development too, which is why we created the Mastering Laravel community.