Question

I’ve read some guides / tutorials about Symfonys event system. But I am still not sure about the naming best practice. Unfortunatelly most documentations use default scenarios like login, etc. So here is an example from a game:

A command evaluations some kind of match result. It fires an appropriate event like this:

$dispatcher->dispatch('game_bundle.match_won', new MatchWonEvent($match, $winner));

Now I want to register several listeners to handle this event, like for example one for posting this to the winner’s Facebook page and another one to book an achievement for the winner. In the examples I found the listener handling the login event was mainly called something like LoginListener, but shouldn’t this name relate to the actual use of it instead of the event it is related to? Because now in my example I would need a MatchWonListener, but should that contain both the Facebook and the achievement logic? That would make the event system useless then… Wouldn’t it be better to have one FacebookListener with an onMatchWon($event) and one AchievementListener with it’s own onMatchWon($event) method? This would also make it easy to add more Facebook-related events into the FacebookListener for example.

I am confused about the naming in the samples and not sure about now. Am I getting it totally wrong?

Answer 1

There’s no “best practice” on how to name events. However, if you name the listener after the event, I think that defeats the purpose of events altogether. The goal is to be able to let different parts of your system interact between each other without coupling and mixing concerns.

So considering you went this far of creating events to separate concerns, why would you go and mix all the different logics into one listener? In that case you might as well just do a direct call instead of dispatching an event.

I’m personally against names like “onMatchWon” because that doesn’t describe what the method does. Let’s say you want to listen to a match won event and update the achievements of the user who won. I’d probably have some user manager service or the sort with a method updateAchievements(MatchWonEvent $event). But I think that’s more of a matter of taste, or convention if you’re willing to.