为什么要将类型对象的动态转换为抛出空引用异常的对象？ [英] Why is casting a dynamic of type object to object throwing a null reference exception?

问题描述

我有以下功能：

public static T TryGetArrayValue<T>(object[] array_, int index_)
{
    ... //some checking goes up here not relevant to question

    dynamic boxed = array_[index_];
    return (T)boxed;
}

当我以下列方式打电话时，

When I call it in the following way,

object a = new object();
object v = TUtils.TryGetArrayValue<object>(new object[] { a }, 0);

（T）boxed throws a null reference例外。

(T)boxed throws a null reference exception.

除了对象之外，我放在其他类型的其他类型，它的工作完全正常。

任何想法，这是什么，为什么它抛出例外？

Any other type I put in there other than "object", it works perfectly fine.
Any ideas what this is, and why it's throwing the exception?

编辑：
我使用动态的原因是为了避免在转换类型时出现异常，例如：

The reason why I use dynamic is to avoid exception when converting types, for example:

double a = 123;
int v = TUtils.TryGetArrayValue<int>(new object[] { a }, 0);

推荐答案

我同意其他回答者说这个样子像一个bug具体来说，它似乎是C＃运行时绑定层中的一个错误，尽管我还没有彻底调查。

I agree with the other answerers who say that this looks like a bug. Specifically it appears to be a bug in C# runtime binding layer, though I have not investigated it thoroughly.

对于错误，我深表歉意。我会将其报告给C＃5测试团队，我们将看看它是否已经在C＃5中被报告和修复。（它在最近的beta版本中复制，因此它不大可能已被报告和修复。 ）如果没有，修复程序不太可能使其成为最终版本。在这种情况下，我们会考虑一下可能的服务版本。

I apologize for the error. I'll report it to the C# 5 testing team and we'll see if it has already been reported and fixed in C# 5. (It reproduces in the recent beta release, so it is unlikely that it has already been reported and fixed.) If not, a fix is unlikely to make it into the final release. In that case we'll consider it for a possible servicing release.

感谢您的关注。如果您觉得输入Connect问题来跟踪它，请随时这样做，并请包括一个链接到此StackOverflow题。如果没有，没问题;测试团队会以任何方式了解它。

Thanks for bringing this to our attention. If you feel like entering a Connect issue to track it, feel free to do so and please include a link to this StackOverflow question. If you don't, no problem; the test team will know about it either way.

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