Circular reference among two .net assemblies

Question

I have two assemblies A & B.

A has existing reference to B and it must be kept that way. Right now I made some changes to B that need to refer to A. So circular

Answer 1

If B now depends on bits of A perhaps you should refactor those bits out into a new assembly C which would be referenced by both A and B.

Answer 2

This is a problem with the language design of C#. In C/C++ you would just use a header to define the interface of the compilation unit and the dependency is resolved.

In C# there are no headers. You have three options

1. 1> merge the assemblies (increase in compilation time and may not
   make sense if the assemblies are functionally unrelated). C# often forces you to do this, even if the assemblies should logically be separate.
2. Dependency injection
3. Creating a third assembly with interfaces which both the modules reference. This accomplishes the dependency injection through a C# language mechanism (interfaces), instead of roll your own; but its the same thing.

Number 3 is typically how these situations are handled in C# but its not as elegant as C/C++ solution to this problem. For large code bases you have to design from the start with this in mind.

Answer 3

Sounds like you are attempting death by interface. Not everything has to be exposed by interface.

A simple answer is to either merge the assemblies, or move the common controls and data types to a third assembly. You only need to interface things if you want a consistent contractual way to access or work with things, and you want to hide the actual implementation.

Answer 4

For issue 1, there is not really a solution other then merge the two projects or do some code generation

For the second, you can do that by implementing the Factory design pattern.

Answer 5

Refactor your code or merge assemblies = don't use circular reference. It is symptom of very bad design.