为什么不能将 .NET 委托声明为静态的?

问题描述

当我尝试编译以下内容时:

When I try to compile the following:

public static delegate void MoveDelegate (Actor sender, MoveDirection args);

我收到一个错误消息:修饰符 'static' 对该项目无效."

I receive, as an error: "The modifer 'static' is not valid for the this item."

我在一个单例中实现这个，有一个单独的类调用委托.问题是当我在另一个类中使用单例实例来调用委托时(从标识符，而不是类型)，无论出于何种原因，我都不能这样做，即使我声明委托是非静态的.显然，只有当且仅当委托是静态的时，我才能通过类型直接引用它.

I'm implementing this within a singleton, with a separate class which calls the delegate. The problem is that when I use the singleton instance within the other class to call the delegate (from the identifier, not the type), I can't do that for whatever reason, even when I declare the delegate non-static. Obviously, I can only refer to it via the type directly if and only if the delegate is static.

这背后的原因是什么?我正在使用 MonoDevelop 2.4.2.

What is the reasoning behind this? I am using MonoDevelop 2.4.2.

更新

在尝试使用以下代码的建议之一后:

After trying one of the suggestions with the following code:

public void Move(MoveDirection moveDir)
{
    ProcessMove(moveDir);
}

public void ProcessMove(MoveDirection moveDir)
{
    Teleporter.MoveMethod mm = new Teleporter.MoveMethod(Move); 
    moveDelegate(this, moveDir);
}

我收到一个处理错误，指出 MoveMethod 必须是一个类型，而不是一个标识符.

I've received a processing error, which states that the MoveMethod must be a type, and not an identifier.

推荐答案

试试这个:

public delegate void MoveDelegate(object o);
public static MoveDelegate MoveMethod;

所以方法变量可以定义为静态的.static 关键字对于 delegate 定义没有意义，就像 enum 或 const 定义一样.

So the method-variable can be defined static. The keyword static has no meaning for the delegate definition, just like enum or const definitions.

如何分配静态方法字段的示例:

An example of how to assign the static method-field:

public class A
{
  public delegate void MoveDelegate(object o);
  public static MoveDelegate MoveMethod;
}

public class B
{
  public static void MoveIt(object o)
  {
    // Do something
  }    
}

public class C
{
  public void Assign()
  {
    A.MoveMethod = B.MoveIt;
  }

  public void DoSomething()
  {
    if (A.MoveMethod!=null)
      A.MoveMethod(new object()); 
  }
}

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