是否有可能重写了IEnumerable在VC ++ / CLI？ [英] Is it possible to override IEnumerable in VC++/CLI?

问题描述

我有它返回一个的IEnumerable 的界面，我想是因为数据来自第三方托管的DLL来实现这一点VC ++ / CLI。

I have an interface which returns an IEnumerable, and I want to implement this in VC++/CLI because the data comes from a third-party unmanaged DLL.

到目前为止，我有：

public ref class MyEnumerable : IEnumerable<SomeType^> {
public:
    virtual IEnumerator<SomeType^>^ GetEnumerator();
}

不过，编译器会抱怨与C2393：共变的返回类型不支持托管类型

But the compiler complains with C2393: "Covariant returns types are not supported in managed types".

这是否意味着我不能执行的IEnumerable S在C ++中，还是有解决方法吗？

Does that mean that I cannot implement IEnumerables in C++, or is there a workaround?

推荐答案

哎呀，这是一个非常笨拙的错误消息。它是什么的真正的抱怨是缺少执行非通用系统::收藏集:: IEnumerable的::的GetEnumerator（）方法。你必须实现它，因为一般的IEnumerable＆LT;>接口继承非泛型之一。东西是有道理的，当仿制药首次加入.NET 2.0，今天没有那么多。我们还挺坚持与.NET 1.x的遗产。

Yikes, it is an awfully clumsy error message. What it is really complaining about is the missing implementation of the non-generic System::Collections::IEnumerable::GetEnumerator() method. You must implement it because the generic IEnumerable<> interface inherits the non-generic one. Something that made sense when generics were first added in .NET 2.0, not so much today. We're kinda stuck with the .NET 1.x legacy.

否则容易当你激活你的秘密去codeR环办，使它看起来像这样的：

Otherwise easy to do when you activate your secret decoder ring, make it look like this:

public ref class MyEnumerable : IEnumerable<SomeType^> {
public:
    virtual IEnumerator<SomeType^>^ GetEnumerator();
private:
    virtual System::Collections::IEnumerator^ GetEnumerator1x() 
               = System::Collections::IEnumerable::GetEnumerator {
        return GetEnumerator();
    }
};

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