Detect Class from Interface Type

Question

I have an interface, and some classes that inherit from it.

public interface IFoo {}
public class Bar : IFoo {}
public class Baz : IFoo {}

If I get the types which implement IFoo, how can I decide if the type will represent a Bar or a Baz (without actually creating the object)?

// Get all types in assembly.
Type[]    theTypes = asm.GetTypes();

// See if a type implement IFoo.
for (int i = 0; i < theTypes.Length; i++)
{
    Type    t = theTypes[i].GetInterface("IFoo");
    if (t != null)
    {
        // TODO: is t a Bar or a Baz?
    }
}

Answer 1

Am I missing something?

theTypes[i] is the type.

Answer 2

if (theTypes[i] == typeof(Bar))
{
    // t is Bar
} 
else if (theTypes[i] == typeof(Baz))
{
    // t is Baz
}

Answer 3

t is neither Bar nor Baz - it is IFoo. theTypes[i] is Bar or Baz.

Answer 4

When you do GetInerface, you're getting the interface only. What you need to do is only get the types that implement that interface like so.

var theTypes = asm.GetTypes().Where(
                                    x => x.GetInterface("IFoo") != null
                                    );

now you can loop through them and do this. or use a switch.

foreach ( var item in theTypes )
  {
     if ( item == typeof(Bar) ) 
      {
         //its Bar
      }
     else if ( item == typeof(Baz) )
      {
        ///its Baz
      }
  }

Answer 5

A strongly-typed solution to "Does Type X implement interface I" that supports analysis/refactoring is:

Type x = ...;
bool implementsInterface = Array.IndexOf(x.GetInterfaces(), typeof(I)) >= 0;

That said, I really have no idea what you are attempting to accomplish.

Answer 6

I think this will help with your problem:

IFoo obj = ...;
Type someType = obj.GetType();
if (typeof(Bar).IsAssignableFrom(someType))
    ...
if (typeof(Baz).IsAssignableFrom(someType))
    ...