Symfony2 Handler vs Listener what the difference?

Question

I need to create listener or handler to provide some actions for AccessDenied exception.

I've looked some sources of standard handlers and listeners, so looks like they can be use for same task.

I also read this:

But only difference I've seen - that handlers often use for handle exceptions.

So, what the real difference between handler and listener in Symfony ?

@zerkms I don't understand the question, can you please clarify what you mean? — Sergio Ivanuzzo, Oct 28 '15 at 20:45
Where did you get that term from? What do you exactly mean when you say "symfony2 handler"? — zerkms, Oct 28 '15 at 20:46
@zerkms For example, standard SecurityBundle contains different handlers, handlers and listeners registered at the same file as services, and as I can understand, I can use handler or listener for the same task — Sergio Ivanuzzo, Oct 28 '15 at 20:53
So check the `SecurityBundle` documentation. It's a bundle-specific thing, not something generic to the symfony2 in general. — zerkms, Oct 28 '15 at 20:55
@zerkms handlers not only used in SecurityBundle. In other bundles too — Sergio Ivanuzzo, Oct 28 '15 at 20:58
And? It's still a bundle specific thing - a bundle can declare: "this thing is called a handler and it does this job". There is no single framework-wide definition for the term and requirements on what it must do. You, as a bundle author are free to call literally any thing "a handler", just because you can. — zerkms, Oct 28 '15 at 20:59

score 5 · Accepted Answer · answered Oct 28 '15 at 21:10

5

Listeners are registered and called when an event occurs. Observer or PubSub patterns are used.

The Handler is more of a strategy pattern that delegates implementation details to class. Which can then be substituted. (composition over inheritance)

The patterns could maybe be interchangeable in some cases, and it's more the intention of the code that calls for one or the other then.

answered Oct 28 '15 at 21:10

NDM

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Important: symfony2 declares the `listener` entity as a part of its Event Dispatcher, but the `handler` term is not officially defined by the framework. So it's not guaranteed that what you stated about the `handler` is true for everything. – zerkms Oct 28 '15 at 21:13
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After reading your answer, I still don't understand anything :)) – Anh Nguyen Jul 28 '16 at 19:04

Symfony2 Handler vs Listener what the difference?

1 Answers1