using System;
using System.Linq;

public interface Alpha
{
	int Value {get;}
}

public class A : Alpha
{
	public int Value { get {return 1;}}
}

public class B : Alpha
{
	public int Value { get {return 2;}}
}

public class C<T> where T:Alpha
{
	public void foo()
	{
		var p = this.GetType().GetGenericArguments();
		if(p.Any(e => e == typeof(A)))
		{
			Console.WriteLine("1".ToString());
		}
		if(p.Any(e => e == typeof(B)))
		{
			Console.WriteLine("2".ToString());
		}		
	}
	public void foo2()
	{
		var t = (T)Activator.CreateInstance(typeof(T));
		Console.WriteLine(t.Value.ToString());
	}
}
					
public class Program
{	
	public static void Main()
	{
		var ca = new C<A>();
		var cb = new C<B>();

		ca.foo();
		cb.foo();
		
		ca.foo2();
		cb.foo2();
	}
}

이래서 사람은 C를 써야...

오 윗분 고수다 저도 도움되었읍니다