C# enum as generic

Question

Cheers! I had a two enums, describing my entityes: Players and guns types:

public enum PlayersType {
    Scout,
    Tank
}

public enum GunsType {
    Machinegun,
    Tesla
}

I had a generic a struct generic class, and 2 realizations of it:

public class EntityType<T> where T: struct, IConvertible {
    public GameObjectType ObjectType;
}

public class PlayerEntity: EntityType<PlayersType> { }

public class TowerEntity: EntityType<GunsType> { }

And i want to create class, who has EntityType field and inherite ScriptableObject class.

I did this:

public class ObjectTypeConfig: ScriptableObject
{
    public EntityType<Enum> EntityType;
}

But its return error:

The type 'System.Enum' must be a non-nullable value type in order to use it as type parameter `T' in the generic type or method.

Does anyone know how can i create necessary field? As a result i'm want to create Class, who will be has a Array of ObjectTypeConfigs, containing Players and Towers Entitiyes.

Answer 1

You declared the property as EntityType<Enum> but EntityType has the generic constraint of EntityType<T> where T : struct.

The struct constraint means:

The type argument must be a value type. Any value type except Nullable can be specified

If You check Enum you see it is a class - and therefore can be assigned null and fails the generic constraints specified.

I suspect you want one of two:

1. Change property to be EntityType<GunsType> or EntityType<PlayersType>
2. Make the ObjectTypeConfig class generic too with the same constraints and then EntityType<T> EntityType

Answer 2

public class ObjectTypeConfig<T>: ScriptableObject where T: struct, IConvertible
{
    public EntityType<T> EntityType;
}