指定受约束的通用类是子类？

Question

I have this class definition:

public abstract class AbstractListViewModel<T>  : AbstractWorkspaceViewModel

So I have a class called AbstractListViewModel that has a generic type, and that is a subclass of AbstractWorkspaceViewModel .

However, I need to constrain T to only be subclasses of AbstractWorkspaceViewModel . I tried the following:

public abstract class AbstractListViewModel<T> where T :
    AbstractWorkspaceViewModel, : AbstractWorkspaceViewModel
public abstract class AbstractListViewModel<T> where T :
    AbstractWorkspaceViewModel : AbstractWorkspaceViewModel

But this syntax is invalid.

So here I am trying to say "A class called AbstractListViewModel that is a subclass of AbstractWorkspaceViewModel and has a generic type that is also a subclass of AbstractWorkspaceViewModel .

How do I define this?

Answer 1

It's the ordering of your constraint. Try this:

public abstract class AbstractListViewModel<T>  : AbstractWorkspaceViewModel
    where T : AbstractWorkspaceViewModel

Answer 2

You want this:

public abstract class AbstractListViewModel<T> : AbstractWorkspaceViewModel
    where T : AbstractWorkspaceViewModel

Answer 3

public abstract class AbstractListViewModel<T> : AbstractWorkspaceViewModel where T : AbstractWorkspaceViewModel