Why do I (sometimes) have to reference assemblies referenced by the assembly I reference?

Question

I have an assembly A that defines an interface with some overloads:

public interface ITransform
{
    Point InverseTransform(Point point);
    Rect InverseTr         


        

Answer 1

That method makes use of something defined in System.Drawing. If you uncomment it then that assembly no longer will by trying to use System.Drawing; hence, no requirement.

Think of it this way, when you go off to perform your action .NET says ok I'm making a call to this guy defined in this assembly and looks for the appropriate code to execute. It can't find it so it throws up it's hands and says I give up you tell me where it is.

Just make it a habit of referencing every DLL you might potentially use.