Find out if a class is derived from an interface or a base class?

[huckfinn19]

Hi,

I need to be able to find out if a class is derived from a particular interface.

I know that it is possible to find out if a class is derived from a base class with the System.Type class with the following code:

public class Class1 {}
public class Class2 : Class1 {}

if(typeof(Class2).IsSubclassOf(typeof(Class1)))
   ...

I need the same thing for interfaces. Does anything exist that does the same kind of job than IsSubclassOf for class inheritance but for interface inheritance?

If not, how could I find out if a class is derived from a particular interface?

Thanks!

Huck

 

[dalchri]

According to what I'm seeing on MSDN IsSubclassOf should work for both object inheritance and interface implementation:

http://msdn.microsoft.com/library/d...tml/frlrfsystemtypeclassissubclassoftopic.asp

You can use this comparison with both interface implementation and object inheritance for a particular object instance as well:

public interface IClass {}
public class Class1 {}
public class Class2 : Class1 : IClass {}

void TestInstance(object obj) {
if (obj is IClass)
...

if (obj is Class1)
...
}

 

[huckfinn19]

Hi!

Thanks for the answer. What about if I am dealing only with types and not instances?

The ultimate goal is a plugin manager in which class types will be registered. They will then be retrived by groups filtrered by their inheritance from a particular interface. This means that in the plugin manager, I deal only with types.

Currently, I am using the following code:

private bool IsDerivedFrom(Type oType, Type oBaseType){
   if(oBaseType.IsInterface){
      ArrayList aoInterfaces = new ArrayList();
      aoInterfaces.AddRange(oType.GetInterfaces());
      if(aoInterfaces.Contains(oBaseType)){
         return true;
      }
   }
   else if(oType.IsSubclassOf(oBaseType)){
      return true;
   }
   return false;
}

Do you know anything simpler? I don't like to have to create an arraylist every time the base type is an interface since it is almost always going to be the case...

Thanks again!

Huck

 

[dalchri]

According to MSDN, this should be sufficient for both interfaces and inheritance:

private bool IsDerivedFrom(Type oType, Type oBaseType){
   return oType.IsSubclassOf(oBaseType)){
}

Is the problem you are running into have to do with multiple layers of inheritance?

interface IClass1 {}
interface IClass2 : IClass1 {}
interface IClass3 : IClass2 {}