什么是静态属性和单身有什么区别？ [英] what's the difference between static property and singleton?

问题描述

辛格尔顿用C＃实现的可能是这样的：

Singleton implemented with C# could be like:

public class Singleton
{
   private static Singleton instance;

   private Singleton() {}

   public static Singleton Instance
   {
      get 
      {
         if (instance == null)
         {
            instance = new Singleton();
         }
         return instance;
      }
   }
}

如果我使用静态实现它像：

If I use static to implement it like:

public static class Globals{
  public static Singleton Instance = new Singleton();
}

以这种方式，应用程序也应该只获得一个实例为整个应用。
那么，这两个方法之间的区别？ ？为什么不使用静态成员直接（更简单和直接的）

in this way, app should also only get the one instance for the entire app. So what's the difference between these 2 approaches? Why not use static member directly(more simple and straight forward)?

推荐答案

如果您使用第二种方式：

If you use the second approach:

public static class Globals{
  public static Singleton Instance = new Singleton();
}

有什么防止有人从做：

Singleton anotherInstance = new Singleton(); // Violates singleton rules

您还没有得到同样的延迟初始化你的第一个版本（尝试）实现，再加上你使用的是公共领域，它不允许你，如果你需要改变，当值取会发生什么未来同样的灵活性。

You also don't get the same lazy initialization your first version (attempts to) achieve, plus you're using a public field, which doesn't allow you the same flexibility in the future if you need to change what happens when a value is fetched.

需要注意的是.NET 4提供了潜在的更好的方法，使一个单：

Note that .NET 4 provides a potentially better approach to making a singleton:

public class Singleton
{
   private static readonly Lazy<Singleton> instance = new Lazy<Singleton>( ()=> new Singleton());

   private Singleton() {}

   public static Singleton Instance
   {
      get 
      {
         return instance.Value;
      }
   }
}

这是很好的，因为它是完全懒和完全线程安全的，但也很简单。

This is nice because it's fully lazy and fully thread safe, but also simple.

这篇关于什么是静态属性和单身有什么区别？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！