Can't cast GenericClass to GenericClass

Asked Oct 25 '19 at 13:46

Active Nov 09 '19 at 20:05

Viewed 49 times

I'm creating a Container that can store any type of data. To get data from container i make method: AnyTypeResult<T> Get<T>(string name) - that returns from the container data that is registered as "name" and cast it to T. The business logic requires that when we Add data to container as GenericType of DerivedClass it is possible to Get it as GenericType of BaseClass. What is the best way to do it.

The same issue is when we want to cast List<B> to List<A>. It can be done witch Linq extension method Cast<T>

public class A {}
public class B : A {}
public class C<T> {}

var a = new C<A>();
var b = new C<B>();

var x = (C<A>)b; // cannot convert type

edited Oct 25 '19 at 14:36

asked Oct 25 '19 at 13:46

H D

https://stackoverflow.com/a/2033921/10608418 might be interesting. Basically the problem is that while everything comming out of a `List` is also of type `A`, if you could cast it it would then be valid to also add an object of type `A` to a `List` which obviously is not allowed. – Oct 25 '19 at 13:55
1

https://dotnetfiddle.net/0OMJwi – Selvin Oct 25 '19 at 13:56
@Selvin IC what you did there;-) (sorry couldn't resist) – Oct 25 '19 at 14:01
@Selvin IC = I see – Sweeper Oct 25 '19 at 14:03
1

Sorry @Selvin, was a bad joke. And @H D. The `Cast` method of Linq doesn't cast it to a a `List` it becomes an `IEnumerable ` (allowed since objects only come out of an `IEnumerable`) and if you call `ToList()` on that it actually creates a new list of type `List `. So there's not real cast of a `List` to a `List` being done. – Oct 25 '19 at 14:15

Can't cast GenericClass to GenericClass

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