牛逼之间的映射 - ＆GT; IHandler＆LT; T＆GT; [英] Mapping between T --> IHandler<T>

问题描述

我有以下接口

public interface IHandler<T>
{
    Handle(T myObject);
}

我想有一个 HandlersManager 类持有对象类型之间的映射到其相应的处理程序，但我不知道怎么我应该定义持有这种映射的对象。

I'd like to have a HandlersManager class with holds a mapping between object types to their corresponding handler, but I'm not sure how I'm supposed to define the object that hold this mapping.

例如，我想有是这样的：

For example, what I'd like to have is this:

typeof(string)  --> instance of IHandler<string>
typeof(MyClass) --> instance of IHandler<MyClass>

我有这么的最好的事情远是定义词典＆LT;类型，对象＆gt; 的映射，但在这种情况下，我将不得不值转换为 IHandler＆LT; T＆GT; 每次我得到它的时候

The best thing I got so far was to define Dictionary<Type, object> for the mapping, but in this case I would have to cast the value to IHandler<T> every time I get it.

有没有更好的解决方案或东西，我已经完全错过了？

Is there a better solution or something that I have completely missed?

推荐答案

这是好，因为它可以得到的只是一个普通的 IHandler＆LT; T＆GT; 接口

That's as good as it can get with only a generic IHandler<T> interface.

为了探索更多的选择，我们可以定义界面的非通用版本：

In order to explore more options, we could define a non-generic version of the interface:

public interface IHandler
{
    void Handler(object myObject);
}

然后，你还可以定义实现了一个通用的抽象基类既 IHandler＆LT; T＆GT; 和 IHandler ：

public abstract class BaseHandler<T> : IHandler, IHandler<T>
{
    public abstract void Handle(T myObject);

    void IHandler.Handle(object myObject)
    {
        ((IHandler<T>)this).Handle((T) myObject);
    }
}

在这一点上，你可以有一个的IDictionary＆LT;类型，IHandler＆GT; 键，可以直接调用 IHandler.Handle 在值你拉出来的：

At this point you can have an IDictionary<Type, IHandler> and you can directly call IHandler.Handle on the values you pull out of it:

var obj = /* whatever */
dictionary[obj.GetType()].Handle(obj);

在另一方面，我们现在有一个额外的接口和抽象基类，只是为了掩盖从用户code，这听起来并不很IM pressive一个演员。

On the other hand we now have an additional interface and an abstract base class just to hide a cast from "user" code, which doesn't sound very impressive.

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