'this' 关键字作为属性

我很了解 C#，但这对我来说很奇怪。在一些旧程序中，我看到过这样的代码：

public MyType this[string name]
{
    ......some code that finally return instance of MyType
}

怎么称呼？这有什么用呢？

It is indexer http://msdn.microsoft.com/en-us/library/6x16t2tx.aspx。声明后，您可以这样做：

class MyClass
{
    Dictionary<string, MyType> collection;
    public MyType this[string name]
    {
        get { return collection[name]; }
        set { collection[name] = value; }
    }
}

// Getting data from indexer.
MyClass myClass = ...
MyType myType = myClass["myKey"];

// Setting data with indexer.
MyType anotherMyType = ...
myClass["myAnotherKey"] = anotherMyType;