Self-referential generic class templates

Is it possible to build the following heterogeneous (generic) linked list data type?

 class MyClass<TPrev, TNext> 
      where TNext : MyClass<TPrev2, TNext2> 
           where TPrev2 : MyClass<TPrev,开发者_开发知识库 TNext>

edit: Notice in particular the new type TNext2 which is not defined.

edit2: ... which makes the above snippet non-functional as written.

No, you can't model what you want. You could do this:

class Link<TPrev, TValue, TNext>
{
    public TPrev  Prev { get; set; }
    public TValue Value { get; set; }
    public TNext  Next { get; set; }
}

But you can't do:

class Link<???, TValue, ???>
{
    public Link<???> Prev { get; set; }
    public TValue Value { get; set; }
    public Link<???> Next { get; set; }
}

The problem is that if you declare that the previous and next elements of your list must also be lists of some generic type, then you've attempted to define a type of infinite size. There's no way to say, "There is no next node after this" because the next node must be a Link<T> for some other link type and you run into an infinite regress.

No, this is not possible because you haven't defined TNext2 or TPrev2 as part of the class definition. You can't have a generic parameter like that unless its an existing type, or is a generic type parameter in the class definition.

But then, if TPrev2 is an existing type, you can't specify a constraint on it like you are trying to do.

Take a look at this blog entry for an interesting idea on the topic. In essence you could do something like this:

public abstract class LinkedListBase<T>
    where T : LinkedListBase<T>
{
    public T Next { get; set; }
    public T Previous { get; set; }
}
public class LinkedListImpl : LinkedListBase<LinkedListImpl>
{
    public string Name { get; set; }
    // all of the value properties go here...
}

So essentially the value itself contains the links to the previous and next.