类型''不能用作通用类型或方法''中的类型参数''。 没有从“到”的隐式引用转换

Question

I am trying to implement some generic in View - Controller classes. My "framework" looks like that:

Controllers:

public interface IController<TView> where TView : IView
{
    // some generic fields / methods definitions
}

public abstract class BaseController<TView> : IController<TView> where TView : IView
{
    // some generic fields / methods implementation
}

public interface IConcreteController
{
    // some specific fields / methods definition
}

public class ConcreteController<TView> : BaseController<TView>, IConcreteController where TView : IView
{
    // specific implementation
}

Views:

public abstract class IView : UserControl // MARKER
{
}

public class BaseView<TController> : IView where TController : IController<IView>
{
    // some generic fields / methods implementation
}

public abstract class IConcreteView : BaseView<IConcreteController>
{
    // some specyfic fields methods definition
}

public class ConcreteView : IConcreteView
{
    // some specific fields methods implementation
}

But I get an error in IConcreteView file:

The type 'IConcreteController' cannot be used as type parameter 'TController' in the generic type or method 'BaseView'. There is no implicit reference conversion from 'IConcreteController' to 'IController'.

What should I fix to get this "template" to work?

Update:

As Ned Stoyanov suggest:

I chenged ConcreteView to:

public class ConcreteView<TController> : BaseView<TController>, IConcreteView where TController : IController<IView>

and IConcreteView to:

public interface IConcreteView

and now it works.

Answer 1

I think the problem is with your definition of IConcreteView

public abstract class IConcreteView : BaseView<IConcreteController>

It iherits from BaseView<IConcreteController> and the class BaseView<TController> has a constraint that TController must be an IController<IView>

BaseView<TController> : IView where TController : IController<IView>

But IConcreteController is not an IController<IView> , it's just a stand alone interface, hence the error message.

I am not sure that the interfaces IConcreteController and IConcreteView are achieving much, I'd just get rid of them altogether.