如何從基類泛型派生泛型類？

Question

我有一個抽象基類通用

public abstract class A<T> where T: Control 
{ 
    protected T _t { get; set; } 

    protected abstract void Method(); 

    protected A(T t) 
    { 
     _t = t; 
    } 
} 

B級從A派生類型的TreeView

public class B<T>: A<TreeView> 
{ 
    protected override void Method() 
    { 
     _t.CallSomeTreeViewMethod(); // ok! 
    } 

    public B (TreeView tree): base (tree) 
    { 

    } 
} 

如何從B級與從TreeView的派生類型派生？

public class C: B<ExtendedTreeView> 
{ 
    protected override void Method() 
    { 
     _t.CallSomeExtendedTreeViewMethod(); 
    } 

    public C (ExtendedTreeView tree): base (tree) 
    { 

    } 
} 

Answer 1

，而不是具體類TreeView添加通用約束：

public class B<T>: A<T> where T:TreeView 
{ 
    protected override void Method() 
    { 
     _t.CallSomeTreeViewMethod(); // ok! 
    } 

    public B (T tree): base (tree) 
    { 

    } 
}