列表<T>只读与私有集 [英] List&lt;T&gt; readonly with a private set

问题描述

如何公开 List 以便它是只读的，但可以私下设置?

How can I expose a List<T> so that it is readonly, but can be set privately?

这不起作用:

public List<string> myList {readonly get; private set; }

即使你这样做:

public List<string> myList {get; private set; }

你仍然可以这样做:

myList.Add("TEST"); //This should not be allowed

我猜你可能有:

public List<string> myList {get{ return otherList;}}
private List<string> otherList {get;set;}

推荐答案

我认为你在混淆概念.

public List<string> myList {get; private set;}

已经只读"了.也就是说，在这个类之外，没有什么可以将 myList 设置为 List

is already "read-only". That is, outside this class, nothing can set myList to a different instance of List<string>

但是，如果您想要一个只读列表，如我不希望人们能够修改列表内容"，那么您需要公开一个 ReadOnlyCollection;.您可以通过以下方式执行此操作:

However, if you want a readonly list as in "I don't want people to be able to modify the list contents", then you need to expose a ReadOnlyCollection<string>. You can do this via:

private List<string> actualList = new List<string>();
public ReadOnlyCollection<string> myList
{
  get{ return actualList.AsReadOnly();}
}

注意，在第一个代码片段中，其他人可以操作列表，但不能更改您拥有的列表.在第二个代码段中，其他人将获得一个他们无法修改的只读列表.

Note that in the first code snippet, others can manipulate the List, but can not change what list you have. In the second snippet, others will get a read-only list that they can not modify.

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