How to check a list for a different instance of a class inheriting generic interface

Question

I have a List<ICar<T>> cars. I want to add new ICar<T> Honda to the list only if it does not already exist in there. The structure is like:

class Honda : IHonda{}
interface IHonda : ICar<T>

class Ford  : IFord{}
interface IFord  : ICar<T>

I only want to put one of each type of car into the list, but only knowing that they are ICar<T> . I don't know ahead of time the list of possible cars. How can this be done?

I was thinking something like

cars.Any(i => i.GetType().GetInterfaces().Contains(
                    car
                    .GetType()
                    .GetInterfaces()
                    .Where(s =>!cars.GetType().GenericTypeArguments != s.GenericTypeArguments
))))

However, something is wrong with that and I can't quite see a path through this one.

Answer 1

If you have a Type instance corresponding to T then you can use:

Type t = //
Type carType = typeof(ICar<>).MakeGenericType(t);
bool exists = cars.Any(c => carType.IsAssignableFrom(c.GetType()));

Answer 2

I think that you can use

 //get list of all interfaces in the currrent car list
 //you will have to check the contents of yourList as it may contain some types 
 //such as IList / IEnumerable that you will want to filter out.
 var yourList =  list.SelectMany(car => car.GetType().GetInterfaces());

 //check get all interfaces on your car and check if the list contains it
 bool exists = yourCar.GetType().GetInterfaces().Any(c => yourList.Contains(c));

Answer 3

You may be able to compare the elements using the fully qualified name of the type.

CarTypeComparer compareCarTypes = new CarTypeComparer();

if (!List.contains(car, compareCarTypes))
{
   // insert car into list
}

class CarTypeComparer : IEqualityComparer<ICar<T>>
{
   public bool Equals(ICar<T> car1, ICar<T> car2)
   {
      if (car1.GetType().FullName == car2.GetType().Fullname)
      {
          return true;
      }
      else 
      {
          return false;
      }

   }
   // implement GetHashCode() ....
}

Answer 4

Add a CarModel property inside of your ICar interface,and then implement it in your classes.For example in Honda class:

public string CarModel { get { return "Honda"; } }

you can check CarModel property in your query and ofcourse you can group your cars by CarModel,i hope this helps..