ReadOnlyNameValueCollection（从 ConfigurationManager.GetSection 读取）
好吧，所以......
<section name="test" type="System.Configuration.NameValueFileSectionHandler" />
<test>
<add key="foo" value="bar" />
</test>
var test = ConfigurationManager.GetSection("test");
到目前为止一切顺利。调试器显示 test 包含一个键 foo。
但是 GetSection 返回 object，所以我们需要一个强制转换：
var type = test.GetType();
// FullName: System.Configuration.ReadOnlyNameValueCollection
// Assembly: System
好的，这应该很简单。所以......
using System;
var test = ConfigurationManager
.GetSection("test") as ReadOnlyNameValueCollection;
错误！
命名空间 System.Configuration 中不存在类型或命名空间 ReadOnlyNameValueCollection。您是否缺少程序集引用？
呃...wtf？
转换为 System.Collections.Specialized.NameValueCollection 可使代码正常工作，但我不太明白为什么会出现错误。
在 MSDN 上搜索 ReadOnlyNameValueCollection 显示根本没有关于此类的文档。它似乎不存在。然而我的代码中有一个这种类型的实例。
Ok, so.....
<section name="test" type="System.Configuration.NameValueFileSectionHandler" />
<test>
<add key="foo" value="bar" />
</test>
var test = ConfigurationManager.GetSection("test");
So far so good. The debugger shows test contains one key, foo.
But GetSection returns object, so we need a cast:
var type = test.GetType();
// FullName: System.Configuration.ReadOnlyNameValueCollection
// Assembly: System
Ok, this should be simple enough. So....
using System;
var test = ConfigurationManager
.GetSection("test") as ReadOnlyNameValueCollection;
error!
The type or namespace ReadOnlyNameValueCollection does not exist in the namespace System.Configuration. Are you missing an assembly reference?
err... wtf?
A cast to System.Collections.Specialized.NameValueCollection gets the code working, but I don't really understand why the error.
And a search for ReadOnlyNameValueCollection on MSDN shows there is no documentation on this class at all. It doesn't seem to exist. Yet I have an instance of that type in my code.
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System.Configuration.ReadOnlyNameValueCollection是 System.dll 程序集的一个内部类。所以你不能从你的代码中引用它。不过，它派生自 System.Collections.Specialized.NameValueCollection，因此您可以通过强制转换来实现此目的。System.Configuration.ReadOnlyNameValueCollectionis aninternalclass to the System.dll assembly. So you can't refer to it from your code. It derives fromSystem.Collections.Specialized.NameValueCollection, though, so that's why you're able to do that with the cast.