在这个例子中可以消除类型参数的重复吗？

Question

我有一个MVP的实现，用于域模型中的项目列表。

我的问题一般是如何（或我可以）摆脱具体的View和Presenter中类型参数的重复？

我倾向于认为我遇到了限制，不得不忍受重复或重新设计课程。另一种选择是我错过了一些明显的东西。无论如何，这就是我在这里问的原因。

具体来说，如果你有：

interface IA<T2, T3> { }
class C<T1, T2, T3> where T1 : IA<T2, T3>

我可以让编译推断出类型参数T2和T3，结果如下：

interface IB : IA<int, string>
class D : C<IB> { } // can't do this

这个编译。重复参数为Note, string和Attachment, string。

// Abstract View
public interface IView<TItem, TKey>
{
   void Fill(TItem[] items);
   event SelectEvent<TKey> SelectionChanged;
   event MessageEvent Add;
}

// Event Delegates
public delegate void SelectEvent<TKey>(TKey selectedValue);
public delegate bool MessageEvent();

// Model Entities
public class Note { }
public class Attachment { }

// Abstract Presenter
public abstract class Presenter<TView, TItem, TKey> where TView : IView<TItem, TKey>
{
   protected TKey SelectedValue { get; private set; }
   protected TView View { get; set; }
   public Presenter(TView view)
   {
       View = (TView)view;
       View.SelectionChanged += OnSelectionChangedInternal;
       View.Add += OnAdd;
   }
   void OnSelectionChangedInternal(TKey selectedValue) {
       this.SelectedValue = selectedValue;
       OnSelectionChanged(selectedValue);
   }
   protected abstract void OnSelectionChanged(TKey selectedVaule);
   protected abstract bool OnAdd();
}

// Concrete Views
public interface INotes  : IView<Note, string> {  }
public interface IAttachments : IView<Attachment, string> { }

// Concrete Presenters
public class NotesPresenter : Presenter<INotes, Note, string> { 
   public NotesPresenter(INotes view)  : base(view) { }
   protected override void OnSelectionChanged(string publisherName) { }
   protected override bool OnAdd() { return false; }
}
public class AttachmentsPresenter : Presenter<IAttachments, Attachment, string> {
   public AttachmentsPresenter(IAttachments view) : base(view) { }
   protected override void OnSelectionChanged(string publisherName) { }
   protected override bool OnAdd() { return false; }
}

Answer 1

对演示者稍作修改。改为推断你的观点。由于您的具体视图实现了正确的界面，因此它可以工作见下面的代码。

// Abstract View
public interface IView<TItem, TKey>
{
    void Fill(TItem[] items);
    event SelectEvent<TKey> SelectionChanged;
    event MessageEvent Add;
}

// Event Delegates
public delegate void SelectEvent<TKey>(TKey selectedValue);
public delegate bool MessageEvent();

// Model Entities
public class Note { }
public class Attachment { }

// Abstract Presenter
public abstract class Presenter<TItem, TKey>
{
    protected TKey SelectedValue { get; private set; }
    protected IView<TItem, TKey> View { get; set; }
    public Presenter(IView<TItem, TKey> view)
    {
        View = view;
        View.SelectionChanged += OnSelectionChangedInternal;
        View.Add += OnAdd;
    }
    void OnSelectionChangedInternal(TKey selectedValue)
    {
        this.SelectedValue = selectedValue;
        OnSelectionChanged(selectedValue);
    }
    protected abstract void OnSelectionChanged(TKey selectedVaule);
    protected abstract bool OnAdd();
}

// Concrete Views
public interface INotes : IView<Note, string> { }
public interface IAttachments : IView<Attachment, string> { }

// Concrete Presenters
public class NotesPresenter : Presenter<Note, string>
{
    public NotesPresenter(INotes view) : base(view) { }
    protected override void OnSelectionChanged(string publisherName) { }
    protected override bool OnAdd() { return false; }
}

public class AttachmentsPresenter : Presenter<Attachment, string>
{
    public AttachmentsPresenter(IAttachments view) : base(view) { }
    protected override void OnSelectionChanged(string publisherName) { }
    protected override bool OnAdd() { return false; }
}