Referencing an external .NET DLL provided by another application in C#

Question

I have a C# project which references a DLL (call it external DLL) which comes with another application. When I build my project, due to the reference, the external DLL gets automatically added to my project output. And when I run my project it loads the external DLL from my project folder.

The other application, which the external DLL belongs to, is developed by another team and the DLL is regularly updated. I don't want to package their DLL with my project. Instead I would like to have my project load their DLL when executed -- rather than pick the DLL copy from my project's folder.

Now I know that this is possible through reflection. I know that I can do an "Assembly.Load" and pick the DLL. But because I use the types from the external DLL all through my code, I would like the code to be statically type checked.

Here's what I would like:

1. Be able to compile my project by referencing the external DLL and thus get static type checking.
2. When the project is run, the external DLL is picked up from the other application's folder and not the copy of the DLL which is in my project's output folder.

Is there any way to solve this problem? Is there some middle ground between adding a reference and using reflection?

Answer 1

The most immediete solution to your problem is to change the properties of the reference. There is a setting called Copy Local. Set that to false and it'll stop copying the DLL to your project's output. You can access the properties of the reference by expanding the references folder in your solution, right-clicking on the reference in question, and clicking properties to open the properties pane.

The fact that Visual Studio copies the DLL to your project's output folder at build time doesn't really matter to the .Net Framework at runtime. All that matters is that the assemblies you reference are available to the framework either in the paths it searches or in the global assembly cache.