Question

I have a set of classes that inherit from the same base class and I need to create a factory method for instantiation of the different base class implementations based on the GuidAttribute attached to the implementing class. So basically the scenario is like this:

abstract class Foo
{
   /* ... */
   public static Foo Create(Guid guid) {
      Type type;
      // Resolve the type ?
      return Activator.CreateInstance(type) as Foo;
   }
}

[Guid("<guid1>")]
class Bar : Foo { ... }

[Guid("<guid2>")]
class Baz : Foo { ... }

Is there any other way than iterating all the types in the loaded assemblies and caching the results?

Answer 1

It wouldn’t be automatic but you could simply build a Dictionary<Guid,Type> or if there’s a common interface/class in each assembly (ala plugin architecture) request it register the types accordingly.

There’s no need to use reflection for everything 🙂 I find it less elegant in many cases.