C# – How to find all the classes which implement a given interface

c++reflection

Under a given namespace, I have a set of classes which implement an interface. Let's call it ISomething. I have another class (let's call it CClass) which knows about ISomething but doesn't know about the classes which implement that interface.

I would like that CClass to look for all the implementation of ISomething, instantiate an instance of it and execute the method.

Does anybody have an idea on how to do that with C# 3.5?

Best Solution

A working code-sample:

var instances = from t in Assembly.GetExecutingAssembly().GetTypes()
                where t.GetInterfaces().Contains(typeof(ISomething))
                         && t.GetConstructor(Type.EmptyTypes) != null
                select Activator.CreateInstance(t) as ISomething;

foreach (var instance in instances)
{
    instance.Foo(); // where Foo is a method of ISomething
}

Edit Added a check for a parameterless constructor so that the call to CreateInstance will succeed.