I have this method:
void SomeMethod<T,V>() where T:V
{
List<T> listT = getT();
List<V> listV = listT.ToList<V>()
}
Its says that listT dont contains a ToList() method.
The above implementation doesn't work. But it works with concrete classes, like below:
interface Ifoo{}
class Bar : Ifoo{}
List<Bar> bar = getBar();
List<Ifoo> bar2 = bar.ToList<Ifoo>()
Why is that? How can I make the method works with those generics constraint?
The reason why bar.ToList<Ifoo>() works is because the compiler can be assured Bar implements Ifoo.
However, when you are in the generic context, even with the constraints that T is V the compiler cannot resolve the extension method (even though we assume it should be capable of it).
It's likely you just want to use Cast... Assuming T can be cast to V:
Casts the elements of an IEnumerable to the specified type
Example
List<V> listV = getT().Cast<V>().ToList();