How to make my dll loadable from codebase only?

Question

My project(some kind of processing engine) is separated into 2 dlls: one with interface declarations and one with functionality.Usually the project is used by external Delphi project via COM technology.

Lets say my program slices fruits. External delphi programm creates Fruit object and fills its properties: weight (int), Name (string) and ProgressUpdater (of type IProgressUpdater which is declared in second dll with interfaces).After this exst programm creater Slicer, makes Slicer.AddFruit(newFruit) and calls Slicer.Slice().

Nothing special. In real life delphi project is Outlook addin. But here is the problem - sometimes some VSTO addins makes Outlook work in "shadow copy files" mode, so when delphi project starts and creats Slicer object, our c# assembly will be put in temp folder and assembly will be created with this local path. Well... this is still not an issue. But the problem is when delphi project creates newFruit and then passes ProgressUpdater object, in my Slicer assembly I can not get external ProgressUpdater: "Return argument has an invalid type", but still can get field with simple types(Weight, Name).

It only happens when shadowCopyFiles mode is on. So my guess is - external ProgressUpdater's assembly and Slicer assembly are placed to different places, so they can not be passed. My question is how to avoid my dll being "shadow copied"? Or is there some different solution?

Answer 1

So as a result I still have no answer for exact question. But the problem is solved (thanks to HansPassant) by using GAC, because assemblies at GAC will be never shadow-copied (actually linker will always first probe assemblies in GAC and then in other places).

Possible answer to the question is to go currentDomain.AssemblyResolve way, but I could not apply this solution to dll which contains public interfaces(types) only. Maybe it will be suitable solution for some cases.

Answer 2

You can use reflection to load DLL dynamically from any location you want. If you can go this way, I can provide further code for loading DLLs.