Thoughts on implementing the *.Abstractions libraries pattern used in dotnet core?

[mchandschuh]

In general its preferable to only take dependencies that you actually depend on. The dotnet core team took this to heart and broke out several *.Abstractions libraries so you could reference all of the concepts pertaining to a particular feature set without having to take on any of the dependencies required by the implementation.

If you're not familiar with this pattern, I recommend you take a look at the Microsoft.Extensions.* nuget packages.

My primary motivation is due to my solution structure. Each service defines a *.protocols library. I've grown to accept that these protocol libraries need to take a hard dependency on akka core. Just moments ago I went to add a stream ref to a message and was reminded that my *.protocols library that would ideally have zero dependencies (except maybe other projects w/out dependencies, domain types, DTOs, common abstractions, etc) is now cluttered w/ akka core and akka streams. I'm starting to get nervous for when we start clustering our services and one unlucky protocol will more than likely need a reference to Akka.Cluster.

Is there an appetite for making this change? It would absolutely be a breaking change, although there are ways to have both co-exist. Both here meaning the *.Abstractions libraries as well as the current set of libraries.

EDIT: I did some playing around w/ msbuild and it looks like it shouldn't be too hard to automate the creation of *.Abstractions libraries as part of ci/cd. I wouldn't recommend this as it would require some heuristic for deciding which files (or portions thereof) to include. Abstractions libraries should contain the abstractions and data types (sans behavior) for the most fundamental concepts contained within the actual implementation library. It does require more maintenance and time to sift through everything, but at the end of the day we'll end up with much cleaner dependency diagrams.

[Zetanova]

+1 It would already be very greate to extract ICanTell, IActorRef and related things into a base library.

[Zetanova]

@mchandschuh As workaround create one or more base nuget lib yourself where you put your common dependencies.
Including Microsoft.Extensions.*.

[Aaronontheweb]

I'm not really convinced the juice is worth the squeeze here - it's hard to decouple the base abstractions, like IActorRef, from their implementations, extension methods (i.e. .Ask) and others. Not really interested in undertaking all of that for the sake of achieving something that is more "technically pure" than what we have today.