问题描述
我看到了一些利用属性的例子，例如(作为动态工厂的地图)http://msdn.microsoft.com/en-us/magazine/cc164170.aspx
I saw some of the examples of utilize attribute, e.g. (as a map for dynamic factory) http://msdn.microsoft.com/en-us/magazine/cc164170.aspx
只是想知道使用属性有什么好处?我可以在 http://msdn.microsoft.com/上找到参考资料zh-CN/z0w1kczw(VS.80).aspx但是，我不确定何时以及为什么要尝试使用它.
Just wondering what is the advantage of using attribute? I can find the reference on http://msdn.microsoft.com/en-gb/z0w1kczw(VS.80).aspx however, I am not sure when and why should I try to use it.
推荐答案
在 .NET Framework 中，可以使用属性的原因有很多——比如
In the .NET Framework, attributes can be used for many reasons -- like
定义哪些类是可序列化
Defining which classes are serializable
选择公开的方法网络服务
Choosing which methods are exposed in a Web service
Attributes 允许我们在设计时将 descriptions 添加到类、属性和方法中，然后可以在运行时通过反射进行检查.
Attributes allow us to add descriptions to classes, properties, and methods at design time that can then be examined at runtime via reflection.
考虑这个例子:
假设你有一个类，它有一个旧版本的方法，由于任何原因仍在使用，现在你想出了一个新版本的类，它很好地利用了 Generic List 和 LINQ，并有了一个新方法出于类似目的.您希望开发人员更喜欢在您的库的更高版本中提供的新版本.你会怎么做?一种方法是写在文档中.更好的方法是使用属性如下.
Say you have a class which has a method from older version which is still in use for any reason and now you have come up with a new version of the class which makes fantastic use of Generic List and LINQ and has a new method for similar purpose. You would like developers to prefer the new one provided in the later version of your library. How will you do that ? One way is to write in the documentation. A better way is to use attribute as follow.
public class AccountsManager
{
[Obsolete("prefer GetAccountsList", true)]
static Account[] GetAccounts( ) { }
static List<Account> GetAccountsList( ) { }
}
如果在编译程序时使用了 obsolete 方法，开发者会得到这个信息并做出相应的决定.
If an obsolete method is used when the program is compiled, the developer gets this info and decides accordingly.
AccountManager.GetAccounts() 已过时:更喜欢 GetAccountsList
AccountManager.GetAccounts() is obsolete: prefer GetAccountsList
我们还可以创建和添加 自定义属性根据要求.
We may also create and add Custom Attributes as per requirements.
参考:
- 在 C# 中使用属性
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