如何创建现有对象的新版本 [英] How do I create a new version of an existing object

问题描述

我有几个继承自 BaseMessage 类的类继承自 IMessage 界面。有一个名为 Requeue（）的 BaseMessage 方法。此方法应使用新的到期日期时间创建新版本的继承消息。



问题是 Requeue（）方法不知道它自己的类是什么。



我试过以下内容：

Hi,

I have several classes that inherit from an abstract BaseMessage class which inherits from the IMessage interface. There is a BaseMessage method called Requeue(). This method should create a new version of the inherited message with a new Due datetime.

The issue is that the Requeue() method has no idea what it's own class is.

I tried the following:

public IMessage Requeue()
{
    var message = this;

    //set the shared field values
    ... 
    
    //Serialize it up (also a BaseMessage method)
    message.SerializedData = Serialize();
    
    message.Save();
    return message;
}

这不起作用。似乎var消息只是成为原始对象的引用，这会破坏东西。



然后我尝试了

This doesn't work. It appears that the var message just becomes a ref to the original object, which breaks stuff.

So then I tried

public static IMessage Requeue(IMessage m)
{
    var message = m;

    //etc
    ...
}

我认为 m 将按值传递，因为它是c＃默认，但我有同样的问题。



所以最终我将 BaseMessage 改为非抽象（什么是为此工作？）所以我至少可以通过使用以下方法假装：

I figured that m would be passed by value as that's the c# default, but I have the same problem.

So eventually I changed BaseMessage to non-abstract (what's the work for that?) so I could at least "fake it" by using the following:

public IMessage Requeue()
{
    IMessage message = new BaseMessage();

    //blah
    ...

    //fake the class type here.  It's the place it is really needed
    message.SerializedData = Serialize();
            
    message.Save();

    return message;
            
}

目前的问题是保存（）还使用 Serialize（）



我想我可以得到另一个 IMessage 在我 Save（）之前使用 DeSerialize（）但感觉就像我在沿着线路进一步追逐解决方案比我需要的更多。



我想让这些类尽可能简单，并将尽可能多的代码放在 BaseMessage 尽可能抽象，因为我想把项目交给一个大三来维护。添加新消息并将其作为插件上传应该成为标准做法。



有没有一种方法可以克隆原始消息而不提及原始消息？我确定我应该知道这个知道> _<< br mode =hold/>

谢谢^ _ ^

Andy

The current issue is that Save() also uses Serialize()

I figured I could get another IMessage by using DeSerialize() before I Save() but it feels like I'm chasing down the solution further along the line than I need to.

I want to keep these classes as simple as possible and put as much of the code in the BaseMessage abstract as I can because I want to hand the project over to a junior to maintain. Adding new messages and uploading them as plugins should become standard practice.

Is there a way I can "Clone" the original message without there being a reference to the original? I'm sure I should know this by know >_<<br mode="hold" />
Thanks ^_^
Andy

推荐答案

如何添加 abstract 虚拟方法来创建克隆对象？

How about adding a abstract virtual method to create the cloned object?

protected virtual IMessage Clone()
{
    return (IMessage)Activator.CreateInstance(GetType());
}

public IMessage Requeue()
{
    var message = Clone();
    if (ReferenceEquals(message, this))
    {
        throw new InvalidOperationException("Clone must return a different object!");
    }
 
    //set the shared field values
    ... 
    
    //Serialize it up (also a BaseMessage method)
    message.SerializedData = Serialize();
    
    message.Save();
    return message;
}

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