设计帮助 - 多态事件处理 [英] Design Help – Polymorphic Event Handling

问题描述

问题的设计 - 多态事件处理

Design Question – Polymorphic Event Handling

目前我正在试图减少数量的事件在我的当前项目手柄。我们有超过USB发送数据的多个系统。我现在有一个例行的信息读取并解析初始头的细节，以确定消息来自哪个系统。标头是有一点不同，所以我创建了EventArgs的是不一样的。然后，我通知更改所有的观察者。所以我现在所拥有的是以下内容：

I’m currently trying to reduce the number of Event Handles in my current project. We have multiple systems that send data over USB. I currently have a routine to read in the messages and parse the initial header details to determine which system the message came from. The headers are a little different, so the EventArgs I created are not the same. Then I notify all "observers" of the change. So what I have right now is the following:

public enum Sub1Enums : byte
{
    ID1 = 0x01,
    ID2 = 0x02
}

public enum Sub2Enums : ushort
{
    ID1 = 0xFFFE,
    ID2 = 0xFFFF
}

public class MyEvent1Args
{
    public Sub1Enums MessageID;
    public byte[] Data;
    public MyEvent1Args(Sub1Enums sub1Enum, byte[] data)
    {
        MessageID = sub1Enum;
        Data = data;
    }
}

public class MyEvent2Args
{
    public Sub2Enums MessageID;
    public byte[] Data;
    public MyEvent2Args(Sub2Enums sub2Enum, byte[] data)
    {
        MessageID = sub2Enum;
        Data = data;
    }
}

Form 1代码

Form1 code

public class Form1
{
    public delegate void TestHandlerCurrentlyDoing(MyEvent1Args eventArgs1);
    public delegate void TestHandlerCurrentlyDoingAlso(MyEvent2Args eventArgs2);

    public event TestHandlerCurrentlyDoing mEventArgs1;
    public event TestHandlerCurrentlyDoingAlso mEventArgs2;

    public Form1()
    {
        mEventArgs1 += new TestHandlerCurrentlyDoing(Form1_mEventArgs1);
        mEventArgs2 += new TestHandlerCurrentlyDoingAlso(Form1_mEventArgs2);
    }

    void Form1_mEventArgs2(MyEvent2Args eventArgs2)
    {
        // Do stuff here
        Sub2Enums mid = my_event2_args.MessageID;
        byte[] data = my_event2_args.Data;
    }

    void Form1_mEventArgs1(MyEvent1Args eventArgs1)
    {
        // Do stuff here
        Sub1Enums mid = my_event1_args.MessageID;
        byte[] data = my_event1_args.Data;
    }

和在分析算法，我有这样的事情基于它是一个消息

And in the parse algorithm I have something like this based on which message it is:

void ParseStuff()
{
    if (mEventArgs1 != null)
    {
        mEventArgs1(new MyEvent1Args(Sub1Enums.ID1, new byte[] { 0x01 }));
    }
    if (mEventArgs2 != null)
    {
        mEventArgs2(new MyEvent2Args(Sub2Enums.ID2, new byte[] { 0x02 }));
    }
}

我真正想要做的是这样的：

What I really want to do is this:

public class Form1
{
    public delegate void TestHandlerDesired(MyEvent1Args eventArgs1);
    public delegate void TestHandlerDesired(MyEvent2Args eventArgs2);

    public event TestHandlerDesired mEventArgs;

    public Form1()
    {
        mEventArgs += new TestHandlerDesired (Form1_mEventArgs1);
        mEventArgs += new TestHandlerDesired (Form1_mEventArgs2);
    }
}

和含糊的原因，我们无法做到这一点。所以我的问题是什么是这个问题的一个更好的方法吗？

And for ambiguity reasons we can’t do this. So my question is what would be a better approach to this problem?

推荐答案

如果您正在试图减少事件的数量处理以抽象/简化你要做的编码，然后再进行双重分派设计模式的事件参数将是完美的。它基本上是一个优雅的（但罗嗦）定出必须执行安全类型转换（/是instanceof检查）

If you're trying to reduce the number of event handles in order abstract / simplify the coding you have to do, then applying the Double Dispatch design pattern to your event args would be perfect. It's basically an elegant (but wordy) fix for having to perform safe type casts (/ is instanceof checks)

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