在.NET 2.0中使用擴展方法？

Question

我想這樣做，但得到這個錯誤：

Error 1 Cannot define a new extension method because the compiler required type 'System.Runtime.CompilerServices.ExtensionAttribute' cannot be found. Are you missing a reference to System.Core.dll? [snipped some path stuff]

我這裏，說看到了一些答案，你必須定義此屬性自己。

我該怎麼做？

編輯：這是我有：

[AttributeUsage (AttributeTargets.Assembly | AttributeTargets.Class | AttributeTargets.Method)] 
public sealed class ExtensionAttribute : Attribute 
{ 
    public static int MeasureDisplayStringWidth (this Graphics graphics, string text) 
    { 

    } 
} 

Answer 1

像這樣：

// you need this once (only), and it must be in this namespace 
namespace System.Runtime.CompilerServices 
{ 
    [AttributeUsage(AttributeTargets.Assembly | AttributeTargets.Class 
     | AttributeTargets.Method)] 
    public sealed class ExtensionAttribute : Attribute {} 
} 
// you can have as many of these as you like, in any namespaces 
public static class MyExtensionMethods { 
    public static int MeasureDisplayStringWidth (
      this Graphics graphics, string text) 
    { 
      /* ... */ 
    } 
} 

或者;只需添加對LINQBridge的引用即可。