Loading assemblies and versioning

Question

I\'m contemplating adding some extensibility into an existing app by providing a few predefined interfaces that can be implemented by \"plugins\" dropped at a specific locat

Answer 1

Whatever your reasons may be to avoid your 3 points (which I think are more reliable and apt), you can take advantage of Assembly Resolve Event.

Include code such as following in your core.dll

static Assembly AppDomain_AssemblyResolve(object sender, ResolveEventArgs args)
       {
            //replace the if check with more reliable check such as matching the public key as well
            if (args.Name.Contains(Assembly.GetExecutingAssembly().GetName().Name))
            {
                Console.WriteLine("Resolved " + args.Name + " as " + Assembly.GetExecutingAssembly().GetName());
                return Assembly.GetExecutingAssembly();
            }

            return null;
       }

Bind the above handler before attempting to load your plugins. If you load the plugins in current Appdomain then bind it to AssemblyResolve of current domain.

For e.g.

[SecurityPermission(SecurityAction.Demand, ControlAppDomain = true)]
public static void LoadPlugins()
{
    AppDomain.CurrentDomain.AssemblyResolve += AppDomain_AssemblyResolve;
    Assembly pluginAssembly = AppDomain.CurrentDomain.Load("MyPlugin");
}