C＃4.0“动态”不设置REF /输出变量 [英] C# 4.0 'dynamic' doesn't set ref/out arguments

问题描述

我与 DynamicObject 实验。其中一件事我尝试做的是设置参考值 / 的值了参数，如$ C所示低于$ C。但是，我不能让值 I 和Ĵ在的Main（） 设置正确（即使它们在 TryInvokeMember设置正确（））。有谁知道如何调用与 REF A DynamicObject 对象 / 退出参数，并能够检索方法内部设定的值？

I'm experimenting with DynamicObject. One of the things I try to do is setting the values of ref/out arguments, as shown in the code below. However, I am not able to have the values of i and j in Main() set properly (even though they are set correctly in TryInvokeMember()). Does anyone know how to call a DynamicObject object with ref/out arguments and be able to retrieve the values set inside the method?

class Program
{
    static void Main(string[] args)
    {
        dynamic proxy = new Proxy(new Target());
        int i = 10;
        int j = 20;
        proxy.Wrap(ref i, ref j);
        Console.WriteLine(i + ":" + j); // Print "10:20" while expect "20:10"
    }
}

class Proxy : DynamicObject
{
    private readonly Target target;

    public Proxy(Target target)
    {
        this.target = target;
    }

    public override bool TryInvokeMember(InvokeMemberBinder binder, object[] args, out object result)
    {
        int i = (int) args[0];
        int j = (int) args[1];
        target.Swap(ref i, ref j);
        args[0] = i;
        args[1] = j;
        result = null;
        return true;
    }
}

class Target
{
    public void Swap(ref int i, ref int j)
    {
        int tmp = i;
        i = j;
        j = tmp;
    }
}

更新7/15：
微软声称已经解决了这一问题对.NET的下一个版本的http://connect.microsoft.com/VisualStudio/feedback/details/543101/net-4-0s-dynamicobject-doesn-t-set-ref-out-arguments

更新2012年9月8日：
使用VS​​.NET 2012既.NET 4.0和4.5，经测试证实：它已经固定

Update 9/8/2012: Tested using VS.NET 2012 with both .NET 4.0 and 4.5, confirm: it's already fixed.

推荐答案

这看起来像它的可能的是一个错误 - 大概在 DynamicObject 。如果添加了裹方法代理是这样的：

This looks like it could be a bug - probably in DynamicObject. If you add a Wrap method to Proxy like this:

public void Wrap(ref int x, ref int y)
{
    target.Swap(ref x, ref y);
}

那么尽管这仍然是动态调用（即主要的code 保持不变）的code工作...所以至少一般的如何做一个动态对象的作品层支持传递通过引用。

Then even though this is still called dynamically (i.e. the code in Main stays the same) the code works... so at least the general "how does a dynamic object work" layer supports pass-by-reference.

我怀疑，如果这的是的确实是一个在DLR错误，可能为时已晚修为.NET 4 - 但它是值得上的反正连接因此它可以固定在一个服务包。另外，如果这是一个刻意限制/限制，应明确在MSDN（它是不是现在，据我可以看到）。记录

I suspect if this is indeed a bug in the DLR, it may be too late to fix for .NET 4 - but it's worth reporting on Connect anyway so it can be fixed in a service pack. Alternatively, if this is a deliberate restriction/limitation, it should be clearly documented in MSDN (which it isn't at the moment, as far as I can see).

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