Different location of assemblies stopped the type casting

Question

I am writing a custom Control class in C# for my main project.

There're 2 projects, one for my Control and one for my main project. These 2 projects are in the same solution. I add a reference from my main project to my Control project. I notice that the first time after I drag my Control from the Tool Panel onto my main winform, an assembly folder was generated at the C:\Users\XXX\AppData\Local\Microsoft\VisualStudio\9.0\ProjectAssemblies, and the folder name is something like "jlebh-py01".

The first build is always OK, but after I rebuild my Control class or whole solution, a new assembly folder will be generated at C:\Users\XXX\AppData\Local\Microsoft\VisualStudio\9.0\ProjectAssemblies, and then problem arises, my Control fails to behave well because Visual Studio says that the two types "originates from different location". The error message is as below:

[A]MyControl.TypeXXX cannot be cast to [B]MyControl.TypeXXX. Type A orginates from assemblyXXX at location 'C:\Users\XXX\AppData\Local\Microsoft\VisualStudio\9.0\ProjectAssemblies\jlebh-py01\MyControl.dll' Type B originats from assemblyXXX at location 'C:\Users\XXX\AppData\Local\Microsoft\VisualStudio\9.0\ProjectAssemblies\ue4i-z3j01\MyControl.dll'

If I reference the Control DLL directly instead of through project reference, or never rebuild the Control project after use my Control in the main project, things seem to be OK.

Does anyone knows why? Is it the proper way to develop a control and a main project within the same solution?

Answer 1

From what you explained - it seems that the main project in your solution is not updating the reference to the control library that you have. I have been working in ASP.NET for a couple of years at least, and have had similar problems with referenced assemblies, but there was always a very simple fix to it - Rebuild the main project. This should clean it, and then run a fresh build.

Another thing you can try is add a variable assembly version to your control. In the project properties, assembly information, try set the version number to 1.0.* This will force the last two version numbers be based on the day and the time of the day, and each time you rebuild the control- it will have a different version. As long as the main project keeps the version updated - which it should - there shouldn't be any problems..