存储/传递代表作为变量 [英] storing/passing delegates as variables

问题描述

我是相当新的C＃和正在制定一个办法，实行动态GUI至极采用串行通信。我最初来自C，所以函数指针的概念很熟悉。

Basicly我希望在serial命令已被处理调用一个answerFunction（）函数。
在理论：
我有一个类lbl_txtBox_Pair这是动态地在运行时创建的。
我有一个类comObject它与串行端口进行通信。
我有第三类comPacket持有关于一个串行指令的所有信息。

1. 在类lbl_txtBox_Pair的对象我实例化一个数据包，并告诉它该功能时，串口命令完成应该被调用。


2. 我给包对象的实例comObject。


3. 后beeing处理comObject希望通过调用存储在包对象的代表信号的数据包的原始发送者。





有关某种原因，我无法得到它的工作。它告诉我，包的属性不调用。 ？我做得不对teribly





下面是代码：
第一类中的代码lbl_txtBox_Pair。我在这里创建comPacket，并把它交给comObject

 公共委托无效answerHandler（comPacket包）; 
公共无效txb_value_KeyPress（对象发件人，KeyPressEventArgs E）
 {
如果（e.KeyChar ==（char）的Keys.Return）
 {
 answerHandler answerMethod =新answerHandler（this.processAnswer）; 
 comPacket问题=新comPacket（this.command，answerMethod，1）; 
 comObject.addPacket（问题）; 
} 
} 
  





comPacket的构造。这里委托被存储稍后调用

 公共委托answerFunction; 
公共comPacket（字符串CMD，代表FUNC，INT PRIO）
 {
 this.cmd = CMD; 
 answerFunction = FUNC; 
 this.prio = PRIO; 
} 
  

在comObject数据包得到处理。完成后我要调用存储在数据包的功能。该comObject运行在的方式在不同的线程。

 如果（this.isEndtocken（inputline））
 $ { b $ b听= FALSE; 
 packet.answerFunction（包）; 
} 
  

和这里是被它打破。 packet.answerFunction（包）;不会执行并表示它不能被称为方法。





任何人能看到它出错？我觉得好像委托失去，这是一个代表什么的信息。 ;）
或我必须完全地重组代码中使用其他类型的回调/事件方法




解决方案

更改 comPacket 来采取一个强类型的委托：

 公共answerHandler answerFunction ; 
公共comPacket（字符串CMD，answerHandler FUNC，INT PRIO）
 {
 this.cmd = CMD; 
 answerFunction = FUNC; 
 this.prio = PRIO; 
} 
  

如果你仍想保留委托引用弱类型，您可以利用 DynamicInvoke 而不是： http://msdn.microsoft.com/en-us/library/system.delegate.dynamicinvoke.aspx





编辑：另一种选择，如果你想维持强类型的代表尚未有不同的用途是利用仿制药。您的委托可以被安置在一个通用类，并针对泛型类型配合其签名。




I am fairly new to C# and was working on a a way to implement a dynamic GUI wich uses the serial communication. I originally come from C, so the concept of function pointer is familiar.

Basicly I want to invoke a answerFunction() function when the serial command has been processed. In Theory: I have a Class lbl_txtBox_Pair which is dynamicly created on runtime. I have a Class comObject which communicates with the serial Port. I have a third class comPacket which holds all information regarding one serial command.

1. in an Object of Class lbl_txtBox_Pair I instanciate a Packet and tell it which function should be called when the serial command is finished.
2. I give the packet Object to the comObject Instance.
3. after beeing processed the comObject wants to signal the original sender of the packet by calling the delegate which is stored in the Packet Object.

For some reason I can't get it to work. It tells me that the Attribute of Packet is not callable. Am I doing something teribly wrong?

Here is the Code: first the code in Class "lbl_txtBox_Pair". I create the comPacket here and give it to the comObject.

public delegate void answerHandler( comPacket packet);
public void txb_value_KeyPress(object sender, KeyPressEventArgs e)
{
   if (e.KeyChar == (char)Keys.Return)
   {
      answerHandler answerMethod = new answerHandler(this.processAnswer);
      comPacket question = new comPacket(this.command, answerMethod, 1);
      comObject.addPacket(question);
    }
 }

The constructor of comPacket. Here the delegate gets stored to be called later.

public Delegate answerFunction;
public comPacket(string cmd, Delegate func, int prio)
{
    this.cmd = cmd;
    answerFunction = func;
    this.prio = prio;
}

In the comObject the Packets get processed. When finished I want to call the function stored in the Packet. The comObject runs in a different Thread by the way.

if (this.isEndtocken(inputline))
 {
    listen = false;
    packet.answerFunction(packet);
 }

And here it is were it breaks. packet.answerFunction(packet); wont execute and says it cant be called as Method.

Can anybody see where it goes wrong? I think it seems like the delegate looses the information that it is a delegate or something. ;) Or do I have to completly restructure the code to use other types of callback / Event Methods?

解决方案

Change your comPacket to take a strongly typed delegate:

public answerHandler answerFunction;
public comPacket(string cmd, answerHandler func, int prio)
{
    this.cmd = cmd;
    answerFunction = func;
    this.prio = prio;
}

If you still want to keep the delegate reference weakly typed, you can leverage DynamicInvoke instead: http://msdn.microsoft.com/en-us/library/system.delegate.dynamicinvoke.aspx

EDIT: Another option if you want to maintain strongly typed delegates yet have different usages is to leverage generics. Your delegate can be housed in a generic class and tie its signature against that generic type.

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