IReadOnlyDictionary缺乏协变性

Question

我已阅读相关问题（How to get around lack of covariance with IReadOnlyDictionary?），但我不明白它如何帮助解决我的问题。

这里是Box其可以（使用ITargetBox），并通知有关的变化（使用ITargetSource）进行编辑：

interface IBoxTarget 
{ 
    void DoSomething(); 
} 

interface IBoxSource 
{ 
    event Action SomethingIsDone; 
} 

class Box : IBoxTarget, IBoxSource 
{ 
    public void DoSomething() 
    { 
     // . . . some logic . . . 

     if (SomethingIsDone != null) SomethingIsDone(); 
    } 

    public event Action SomethingIsDone; 
} 

Room是Box的容器。它也实现了两个接口：

interface IRoomTarget 
{ 
    IReadOnlyDictionary<string, IBoxTarget> Boxes { get; } 
} 

interface IRoomSource 
{ 
    IReadOnlyDictionary<string, IBoxSource> Boxes { get; } 
} 

class Room : IRoomTarget, IRoomSource 
{ 
    Dictionary<string, Box> boxes = new Dictionary<string, Box>(); 

    IReadOnlyDictionary<string, IBoxTarget> IRoomTarget.Boxes 
    { 
     get { return boxes; } // Error: "Cannot implicitly convert type ..." 
    } 

    IReadOnlyDictionary<string, IBoxSource> IRoomSource.Boxes 
    { 
     get { return boxes; } // Error: "Cannot implicitly convert type ..." 
    } 
} 

我不希望创建内部Room两个不同的字典。我需要做什么？

Answer 1

在我的特殊情况下，这有助于：

interface IRoomTarget 
{ 
    IBoxTarget this[string name] { get; } 
} 

interface IRoomSource 
{ 
    IBoxSource this[string name] { get; } 
} 

class Room : IRoomTarget, IRoomSource 
{ 
    Dictionary<string, Box> boxes = new Dictionary<string, Box>(); 

    public IBoxTarget IRoomTarget.this[string name] 
    { 
     get { return boxes[name]; } 
    } 

    IBoxSource IRoomSource.this[string name] 
    { 
     get { return boxes[name]; } 
    } 
} 

但我不知道这是普遍的解决方案