IExtension：可扩展对象模式：它是如何工作的？

发布于 2024-07-16 15:18:52 字数 1988 浏览 8 评论 0原文

我正在探索使用 C# 中的 (IExtension, IExtensibleObject) 接口的可扩展对象模式，我提供了一个非常简单的示例，用于将本地日期转换为 UTC，反之亦然：

public class BaseObject : IExtensibleObject<BaseObject> 
{
    private DateTime _startDate;
    private ExtensionCollection<BaseObject> _extensions;

    public DateTime StartDate
    {
        get { return _startDate; }
        set { _startDate = value; }
    }

    public BaseObject()
    {
        StartDate = DateTime.Now;
        _extensions = new ExtensionCollection<BaseObject>(this); 
    }

    #region IExtensibleObject<BaseObject> Members

    public IExtensionCollection<BaseObject> Extensions
    {
        get 
        {
            return _extensions;
        }
    }

    #endregion
}

public class DateTimeConverterExtension : IExtension<BaseObject>
{
    private BaseObject _owner;

    #region IExtension<BaseObject> Members

    public void Attach(BaseObject owner)
    {
        _owner = owner;
        _owner.StartDate = owner.StartDate.ToUniversalTime();
    }

    public void Detach(BaseObject owner)
    {
        _owner.StartDate = _owner.StartDate.ToLocalTime();
    }

    #endregion
}

class Program
{
    static void Main(string[] args)
    {
        BaseObject obj = new BaseObject();
        Console.WriteLine("Local Time: "+obj.StartDate);

        obj.Extensions.Add(new DateTimeConverterExtension());


        Console.WriteLine("UTC: "+obj.StartDate);

        DateTimeConverterExtension ext = obj.Extensions.Find<DateTimeConverterExtension>();
        obj.Extensions.Remove(ext);

        Console.WriteLine("Local Time: "+obj.StartDate);
    }
}

输出：

当地时间：4/13/2009 11:09:19 AM
世界标准时间：2009 年 4 月 13 日上午 5:39:19
当地时间：2009年4月13日 11:09:19 AM
按任意键继续。。 .

所以它有效，问题是：

当程序调用 IExtensionCollection.Add 和 IExtensionCollection.Detach 方法时，.Net 框架如何调用“Attach”和“Detach”？填写我在这里缺少的内部详细信息。

原文

I was exploring about Extensible object pattern using (IExtension, IExtensibleObject) interfaces in C#,
I came with a very simple example to convert dates to UTC from local and vice-versa:

public class BaseObject : IExtensibleObject<BaseObject> 
{
    private DateTime _startDate;
    private ExtensionCollection<BaseObject> _extensions;

    public DateTime StartDate
    {
        get { return _startDate; }
        set { _startDate = value; }
    }

    public BaseObject()
    {
        StartDate = DateTime.Now;
        _extensions = new ExtensionCollection<BaseObject>(this); 
    }

    #region IExtensibleObject<BaseObject> Members

    public IExtensionCollection<BaseObject> Extensions
    {
        get 
        {
            return _extensions;
        }
    }

    #endregion
}

public class DateTimeConverterExtension : IExtension<BaseObject>
{
    private BaseObject _owner;

    #region IExtension<BaseObject> Members

    public void Attach(BaseObject owner)
    {
        _owner = owner;
        _owner.StartDate = owner.StartDate.ToUniversalTime();
    }

    public void Detach(BaseObject owner)
    {
        _owner.StartDate = _owner.StartDate.ToLocalTime();
    }

    #endregion
}

class Program
{
    static void Main(string[] args)
    {
        BaseObject obj = new BaseObject();
        Console.WriteLine("Local Time: "+obj.StartDate);

        obj.Extensions.Add(new DateTimeConverterExtension());


        Console.WriteLine("UTC: "+obj.StartDate);

        DateTimeConverterExtension ext = obj.Extensions.Find<DateTimeConverterExtension>();
        obj.Extensions.Remove(ext);

        Console.WriteLine("Local Time: "+obj.StartDate);
    }
}

Output:

Local Time: 4/13/2009 11:09:19 AM
UTC: 4/13/2009 5:39:19 AM
Local Time: 4/13/2009 11:09:19 AM
Press any key to continue . . .

So it works, the question is:

How does .Net framework invoke "Attach" and "Detach" when IExtensionCollection.Add and IExtensionCollection.Detach methods are invoked by the program? Fill in the internal details which I am missing here.

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一个人的旅程 2024-07-23 15:18:52

Attach 和 Detach 方法由 ExtensionCollection.InsertItem 和 ExtensionsCollection.RemoveItem 调用，分别。这些方法又是由 SynchronizedCollection.Add 和 SynchronizedCollection.Remove 调用的虚拟方法，这是您的代码最终调用的方法。这可以通过使用 Reflector 进行验证。如果您创建了自己的 IExtensionCollection 实现，则无法保证 Attach 和 Detach 会被正确调用。