如何通过类库正确解析DLL引用而不将引用添加到调用项目中

Question

TL:DR How do I reference an assembly only in a class library rather than both the library and the calling project?

I am building a utility library in C# in order to promote code reuse. In this instance, I am wanting to do something things with a TFS server and need to reference several assemblies from the TFS side of things:

• Microsoft.TeamFoundation.Client
• Microsoft.VersionControl.Client
• Microsoft.WorkItemTracking.Client

I include these references in the class library called, say, Utility. I then proceed to wrap objects in those assemblies in helper objects. There are no errors, intellisense works correctly, and so forth.

When I want to use that class library in another project inside the same solution, say, TestCLI, I add a reference to the Utility project by selecting the project from the solution references tab. I can then use the Utility classes without issue, until I go to build.

When I build the solution, it throws an error such as:

The type 'Microsoft.TeamFoundation.VersionControl.Client.BranchObject' is defined in an assembly that is not referenced. You must add a reference to assembly 'Microsoft.TeamFoundation.VersionControl.Client, Version=12.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a

In the past, I have worked around this issue by adding the same references to the calling project (TestCLI) in addition to the class library (Utility). I feel that this is defeating one of the purposes of having a class library and that I've missed a step in order to not have to worry about library references in my calling project.

Is there some way to resolve these dependencies without including the references in both the class library and the calling project? Am I structuring my solutions incorrectly? Am I thinking about class libraries in the incorrect manner?

Answer 1

The references are required because you are exposing objects from the other libraries, and then to use these classes the final program needs the references.

To avoid this you must hide the external objects, through a wrapper, a copy of the class or anything else, it depends primarily on what and why you are exposing those objects.