Hi Sean, thanks for discussing Akka Typed!
The design decision behind splitting the interface into a public and a private part is documented in the ScalaDoc for ActorRefImpl: end users shall not ever see the top two methods because there cannot possibly be a reason to use them—but the implementation will need them. Therefore I felt that internals are leaked by having just one interface. Another (minor) issue is that equality and toString are fixed by the semantics of the interface and the self-type ensures that this contract is not broken. Thankfully, the whole design of Akka Typed is much different from untyped Akka, where this kind of separation was forced by implementation details. In Akka Typed we are free to fold ActorRefImpl into ActorRef and revert the decision. We should then make ActorRef an abstract class, so that it can also safely be used from Java without losing the semantic contract. The downside would remain: exposing methods that don’t belong into user space. May I ask in how far your intended ActorRef implementation would be different from TestProbe or Inbox? Since there is only a single purpose to ActorRef—sending single messages—we should be able to include all needed stub functionality in one implementation; my guess is that your fake/stub/mock would reimplement what is already there but I may well be missing something. Another point that I’d like to hear more about is how you intend to test your behaviors in general. This question stems from some surprise at hearing “hard to test” in conjunction with Akka Typed :-) (given that testability is an explicit design goal) Regards, Roland > 16 aug. 2017 kl. 21:05 skrev Sean Shubin <seanshu...@gmail.com>: > > ActorRef has a self type of ActorRefImpl. This means that if I want to > fake/stub/mock an ActorRef for test purposes, I cannot because I am forced to > know about ActorRefImpl. Instead of users of ActorRef being forced to only > use the ActorRefImpl implementation, ActorRef should be a minimal interface > that only exposes the essential characteristics of an ActorRef, freeing up > users to chose among implementations of ActorRef, including fakes/stubs/mocks > for testing, and an ActorRefImpl for production. As it is designed now, I > don't see how one can easily test akka.typed code without specialized > libraries that know about ActorRefImpl. > > I find that hard to test code is usually a result of design decisions rather > than the inherent nature of the problem, and with careful attention and > imagination one can make code easy to test without having to use a > specialized library. > > I am just starting to learn akka typed, so hopefully I will have time to give > more detailed feedback than just the one example once I am more familiar with > the design. I am hoping that before removing the warning about how the > akka.typed API and semantics may change, the design is refactored to support > a more test driven, design by contract approach. I love the idea of having a > statically typed, event driven option for how I code, so am really glad > akka.typed is being worked on. > > > -- > >>>>>>>>>> Read the docs: http://akka.io/docs/ <http://akka.io/docs/> > >>>>>>>>>> Check the FAQ: > >>>>>>>>>> http://doc.akka.io/docs/akka/current/additional/faq.html > >>>>>>>>>> <http://doc.akka.io/docs/akka/current/additional/faq.html> > >>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user > >>>>>>>>>> <https://groups.google.com/group/akka-user> > --- > You received this message because you are subscribed to the Google Groups > "Akka User List" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to akka-user+unsubscr...@googlegroups.com > <mailto:akka-user+unsubscr...@googlegroups.com>. > To post to this group, send email to akka-user@googlegroups.com > <mailto:akka-user@googlegroups.com>. > Visit this group at https://groups.google.com/group/akka-user > <https://groups.google.com/group/akka-user>. > For more options, visit https://groups.google.com/d/optout > <https://groups.google.com/d/optout>. -- >>>>>>>>>> Read the docs: http://akka.io/docs/ >>>>>>>>>> Check the FAQ: >>>>>>>>>> http://doc.akka.io/docs/akka/current/additional/faq.html >>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user --- You received this message because you are subscribed to the Google Groups "Akka User List" group. To unsubscribe from this group and stop receiving emails from it, send an email to akka-user+unsubscr...@googlegroups.com. To post to this group, send email to akka-user@googlegroups.com. Visit this group at https://groups.google.com/group/akka-user. For more options, visit https://groups.google.com/d/optout.
