C# Multiple constraints
- by John
I have an application with lots of generics and IoC. I have an interface like this:
public interface IRepository<TType, TKeyType> : IRepo
Then I have a bunch of tests for my different implementations of IRepository. Many of the objects have dependencies on other objects so for the purpose of testing I want to just grab one that is valid. I can define a separate method for each of them:
public static EmailType GetEmailType()
{
return ContainerManager.Container.Resolve<IEmailTypeRepository>().GetList().FirstOrDefault();
}
But I want to make this generic so it can by used to get any object from the repository it works with. I defined this:
public static R GetItem<T, R>() where T : IRepository<R, int>
{
return ContainerManager.Container.Resolve<T>().GetList().FirstOrDefault();
}
This works fine for the implementations that use an integer for the key. But I also have repositories that use string. So, I do this now:
public static R GetItem<T, R, W>() where T : IRepository<R, W>
This works fine. But I'd like to restrict 'W' to either int or string. Is there a way to do that?
The shortest question is, can I constrain a generic parameter to one of multiple types?
