blocks|key|1017088|text|是的，ExpandoObject在很大程度上是为了将属性动态添加到“属性包”中。但是，不支持为这样的属性提供getter和setter的概念。如果你仔细考虑一下，这一点可能会很清楚:如果你已经知道getter和setter应该做什么，它就不再是一个动态属性了。您能得到的最接近的方法是实现INotifyPropertyChanged事件，这样您就可以检测到更改。一些示例代码：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1017089|using+System;
using+System.Dynamic;
using+System.ComponentModel;

class+Program+{
++static+void+Main(string[]+args)+{
++++dynamic+obj+=+new+ExpandoObject();
++++obj.test+=+42;+++++//+Add+a+property
++++Console.WriteLine(obj.test);

++++var+inpc+=+(INotifyPropertyChanged)obj;
++++inpc.PropertyChanged+%2B=+inpc_PropertyChanged;
++++obj.test+=+"foo";
++++Console.ReadLine();
++}

++static+void+inpc_PropertyChanged(object+sender,+PropertyChangedEventArgs+e)+{
++++Console.WriteLine("'{0}'+property+changed",+e.PropertyName);
++}

}|code-block|syntax|javascript|1017090|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Yes, ExpandoObject is very much designed to dynamically add properties to a "property bag". The notion of giving such a property an getter and setter is not supported however. Maybe that's clear if you think about it a bit: it wouldn't be a dynamic property anymore if you already know what the getter and setter should do. The closest you could get is implementing the INotifyPropertyChanged event so you can detect changes. Some sample code:

<pre><code>using System;
using System.Dynamic;
using System.ComponentModel;

class Program {
 static void Main(string[] args) {
 dynamic obj = new ExpandoObject();
 obj.test = 42; // Add a property
 Console.WriteLine(obj.test);

 var inpc = (INotifyPropertyChanged)obj;
 inpc.PropertyChanged += inpc_PropertyChanged;
 obj.test = "foo";
 Console.ReadLine();
 }

 static void inpc_PropertyChanged(object sender, PropertyChangedEventArgs e) {
 Console.WriteLine("'{0}' property changed", e.PropertyName);
 }

}
</code></pre>

blocks|key|1231822|text|可以向ExpandoObject添加委托属性，然后这些属性的行为(几乎)就像方法一样。例如，|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1231823|dynamic+obj+=+new+ExpandoObject();
obj.GetDocumentTemplate+=+()+=>+{+...+};
...
obj.GetDocumentTemplate();+//+invokes+delegate|code-block|syntax|javascript|1231824|entityMap^0|3|D|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

It's possible to add delegate properties to an <code>ExpandoObject</code>, which then act (almost) just like methods. e.g.,

<pre><code>dynamic obj = new ExpandoObject();
obj.GetDocumentTemplate = () =&gt; { ... };
...
obj.GetDocumentTemplate(); // invokes delegate
</code></pre>

blocks|key|1231883|text|我想知道如何才能“即时”地将成员添加到类中，并想出了这个示例：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1231884|using+System;
using+System.Collections.Generic;
using+System.Dynamic;

class+Program
{
++++static+void+Main()
++++{
++++++++dynamic+expando+=+new+ExpandoObject();
++++++++var+p+=+expando+as+IDictionary<String,+object>;

++++++++p["A"]+=+"New+val+1";
++++++++p["B"]+=+"New+val+2";

++++++++Console.WriteLine(expando.A);
++++++++Console.WriteLine(expando.B);
++++}
}|code-block|syntax|javascript|1231885|这段代码的要点是，成员A和B在中被定义为字符串文字(硬编码/字符串化)，并通过ExpandoObject的IDictionary接口添加。我们通过直接访问它们并将其输出到控制台来测试密钥的存在和值(并证明概念)。|1231886|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

I wondered how it might be possible to add members to a class "on the fly" and came up with this sample:

<pre><code>using System;
using System.Collections.Generic;
using System.Dynamic;

class Program
{
 static void Main()
 {
 dynamic expando = new ExpandoObject();
 var p = expando as IDictionary&lt;String, object&gt;;

 p["A"] = "New val 1";
 p["B"] = "New val 2";

 Console.WriteLine(expando.A);
 Console.WriteLine(expando.B);
 }
}
</code></pre>

The point of this code snippet is that the members A and B are defined as string literals (hard coded/stringified) in and added via ExpandoObject's IDictionary interface. We test for the keys' existence and values (and prove the concept) by accessing them directly and outputting to console.

blocks|key|1017264|text|到目前为止，答案涵盖了很好的基础知识，但我觉得这篇MSDN+Magazine文章也值得分享：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1017265|http://msdn.microsoft.com/en-us/magazine/ff796227.aspx|offset|length|1017266|它介绍了一些使用动态XML输入动态创建和使用ExpandoObjects的示例。|1017267|entityMap|0|LINK|mutability|MUTABLE|url^0|0|0|1I|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|P|8|@]|9|@$D|Q|E|R|1|S]]|A|$]]|$1|F|3|G|5|6|7|T|8|@]|9|@]|A|$]]|$1|H|3|-4|5|6|7|U|8|@]|9|@]|A|$]]]|I|$J|$5|K|L|M|A|$N|C]]]]

The answers so far cover the basics quite well, but I felt this MSDN Magazine article was worth sharing as well: 

<a href="http://msdn.microsoft.com/en-us/magazine/ff796227.aspx" rel="nofollow">http://msdn.microsoft.com/en-us/magazine/ff796227.aspx</a>

It covers some examples of using dynamic XML input to dynamically create and use ExpandoObjects.

just exploring c# 4. Trying to get my head around all this dynamic stuff. Sorry if this question is silly, no experience in this domain.

If I have an ExpandoObject and want to add public properties (with get and set) to it at runtime, how would I go about doing it?

For example, I have a documentTemplate and a document, which has a property pointing towards the documentTemplate. This documentTemplate has got some tag Titles (eg. Capabilities developed among students), which should be addressed while making the document (eg. Concentration, memory etc.). So as soon as the template is set in the document, I want to create a class, which has properties with same names as the tag titles in the Template, and then using some UI element, such as the PropertyGrid, I can have the user fill in tag values against the tag Titles.

Thanks for reading!

Adding unknown (at design time) properties to an ExpandoObject

我只是在探索c# 4，试图弄明白所有这些动态的东西。抱歉，如果这个问题是愚蠢的，在这个领域没有经验。如果我有一个ExpandoObject，并且想要在运行时给它添加公共属性(使用get和set)，我该怎么做呢？例如，我有一个documentTemplate和一个文档，其中有一个指向documentTemplate的属性...

问向ExpandoObject添加未知(在设计时)属性
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