Add type hinting to wait function

[joelwurtz]

IMO, we should force the type hinting of the wait method.

There is some reason to that :

1. The wait method will probably never be in a PSR so there is probably no BC break upcoming for that
2. Not having this type hinting will mean we allow everything as the value fulfilled / reason, which will induce in every package to check that the return type / reason is correct

WDYT ?

[sagikazarmark]

The wait method will probably never be in a PSR so there is probably no BC break upcoming for that

Why is that?

Not having this type hinting will mean we allow everything as the value fulfilled / reason, which will induce in every package to check that the return type / reason is correct

What will happen, if we switch to a PSR?

[joelwurtz]

Why is that?

Because they will probably say that a promise should use an Event Loop, and by using an event loop you don't need the wait method.

What will happen, if we switch to a PSR?

Provide a compatibilty layer, otherwise we will have to do something like the follwing everywhere we use the value / reason of a promise :

$value = $promise->wait();

if (!$value instanceof ResponseInterface) {
    throw new UnexpectedValueException();
}

[sagikazarmark]

Because they will probably say that a promise should use an Event Loop

I will fight four our wait method.

The promises are actually used INSIDE our libraries now and in case of a PSR, which means the chance of having an invalid value is exactly the same as we would use a PSR Promise implementation. But I am fine with that.

[joelwurtz]

Yeah but if there is a promise PSR having some sort of layer to fix the type hinting would be nice also to avoid duplicate this work everywhere (like a decorated promise with a specific interface). The point here is we use the promise in the context of an http call.

Having something too generic does not relly make sense and imply too many work IMO.