Question

I’m unclear on the differences between

public class MyVehicleCollection<T> where T : Vehicle
{
     private List<T> listofVehicles = new List<T>();

     public void AddVehicle(T v) { listofVehicles.Add(v); }
}

and

public class MyVehicleCollection<Vehicle>
{
     private List<Vehicle> listofVehicles = new List<Vehicle>();

     public void AddVehicle(Vehicle v) { listofVehicles.Add(v); }
}

I don’t see why in both cases its only possible to add types derived from Vehicle to the collection. I also don’t see why i’d need to create additional collection classes for containing Motobike : Vehicle in the non-generic case.

Many thanks in advance.

Answer 1

Your second form is not bound to Vehicle at all:

public class MyVehicleCollection<Vehicle>
{
}

...

var coll = new MyVehicleCollection<string>();

From your description, you don’t seem to need generics at all.

public class MyPlainVehicleCollection  //<Vehicle>  no Type Parameter
{
     private List<Vehicle> listofVehicles = 
             new List<Vehicle>();  // class Vehicle

     public void AddVehicle(Vehicle v) { listofVehicles.Add(v); }
}

also don’t see why i’d need to create additional collection classes for
containing Motobike : Vehicle

You don’t :

var garage = new MyPlainVehicleCollection();
garage.Add(new Motobike ());