Should be something like:Collects all messages.

is it a good idea to do it with for? not foreach? You have flipped$domains and left$catalogues

$domains is usually small array (several items) and$catalogues is often quite big. So thefor-loop is used here (instead ofarray_flip +foreach-loop) in only matter of performance.

I don't really like theexposeMessages() name. What about justgetMessages()?

I don't see any difference between passingarray() andnull for domains. Then I would just usearray $domains = array() without null.

I see@fabpot suggested that. But I don't agree with that. First of all, it makes the argument type dynamic and secondly, there is no semantic difference.

So when you see code like

$translator->getMessages(array());$translator->getMessages(null);

you would think both do something different and look at the implementation what the difference is. But in fact it's the same.

@Tobion agree with you. That how I first time made. Then@fabpot asked to change. But I think it's not critical. Both variants are fine for me.

Whatever. Usearray() if you want to, I don't really care.

Please note what the default means: every domain. It seems wrong to use every domain if you pass an empty list. Null stands for no argument, if you pass no argument to domain, it seems logical to get all domains.

@wouterj It's perfectly right to get every domain if you pass an empty list. The argument filters the required domains (see phpdoc), i.e. an empty filter will return everything. Pretty logical.
Btw, it's the same as inRoute::setSchemes.

What I also find bad is that you can get all messages for all domains, but not for all locales.
I'd propose to simply remove the domains parameter. The logic that it implements can simply be done by the user. And the method should only have a single responsibility, and that is not filtering domains.

@Tobion Frankly, don't see anything bad of allowing to filter messages at the fetch method. It looks natural for me. Confident, that other developers will find it usefull.

Regarding "null vs.array()", I'm like 45/55. Your argument

to get every domain if you pass an empty list.

seems reasonable for me. That's how most UI filters works "empty filter list --> all records". That's why, have implemented it this way first time. But, really don't see a big deal to usenull for all messages. There's only matter of integrity and consistency, and IMHOarray() fits more those requirements.

Yes it might be useful, but everything is useful for someone. The point is,

1. it violates single responsibility
2. is really simply to do in user-land, just `$messages['mydomain']

@Tobion, you are definitely right. It won't be hard to pick proper domains by array's keys in afterwords. I've updated the method, the test and documentation as well.
Thank you.

Missing description that it returnsarray[array] indexed by catalog.

Why is this calculated instead of setting the value explicitly in the data provider?