返回集合为只读 [英] Return collection as read-only

问题描述

我在多线程环境中的对象，保持信息的集合，例如：

I have an object in a multi-threaded environment that maintains a collection of information, e.g.:

public IList<string> Data 
{
    get 
    {
        return data;
    }
}

我现在有返回数据; 包裹一个 ReaderWriterLockSlim 来保护共享冲突的集合。不过，为了以防万一，我想返回集合为只读，这样调用code是无法更改的收集，只有查看的内容已经存在。这是在所有可能的？

I currently have return data; wrapped by a ReaderWriterLockSlim to protect the collection from sharing violations. However, to be doubly sure, I'd like to return the collection as read-only, so that the calling code is unable to make changes to the collection, only view what's already there. Is this at all possible?

推荐答案

如果你唯一的目的是让调用code不犯错误，和修改时，只应阅读一切必要的是集返回不支持添加，删除，接口等。为什么不返回的IEnumerable＆LT;字符串＆GT; ？调用code将不得不投，它们不太可能做不知道他们正在访问属性的内部。

If your only intent is to get calling code to not make a mistake, and modify the collection when it should only be reading all that is necessary is to return an interface which doesn't support Add, Remove, etc.. Why not return IEnumerable<string>? Calling code would have to cast, which they are unlikely to do without knowing the internals of the property they are accessing.

如果您但是意图是prevent从观察其他线程更新调用code，你将不得不回落到已经提到的解决方案，以执行深或浅拷贝根据您的需要。

If however your intent is to prevent the calling code from observing updates from other threads you'll have to fall back to solutions already mentioned, to perform a deep or shallow copy depending on your need.

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