为什么对象实例中的枚举具有静态上下文？ [英] Why an enum in an object instance has a static context?

问题描述

我有以下类：

public class HandleResourceReferencesParams
{
    public Factory Factory { get; set; }
    public DataObject Resource { get; set; }
    public HandleAction Action { get; set; }

    public enum HandleAction
    {
        Activate,
        Disable,
        Terminate
    }
}

以下代码中使用的是：

var parameters = new HandleResourceReferencesParams();
parameters.Factory = context.Factory;
parameters.Resource = resource;
parameters.Action = parameters.HandleAction.Terminate; // Does not compile
HandleResourceReferences(parameters);

通过使用 parameters.HandleAction ，我得到一个编译错误：

By using parameters.HandleAction, I get a compile error:

在非静态上下文中无法访问静态枚举HandleAction

Cannot access static enum 'HandleAction' in non-static context

枚举显然不声明为静态。为什么从对象实例（非静态）引用静态上下文？

The enum is clearly not declared 'static'. Why does it have a static context when it is referenced from an object instance (non static as well)?

编辑：
我已经找到了Tim提到的解决方案（感谢方式）。我只是想了解为什么我得到这个错误。

I already found the solution mentioned by Tim (Thanks by the way). I am just trying to understand why I am getting this error.

推荐答案

错误信息是不幸的，但不幸的是，不能做它...您正在尝试访问类型的成员，而不是类型的实例的成员，但您正在做所以通过一个实例。

The error message is unfortunate, but it's not unfortunate that you can't do it... you're trying to access a member of a type, rather than a member of an instance of the type, but you're doing so "via" an instance.

基本上，这个代码无法编译的原因相同：

Basically, it's the same reason that this code fails to compile:

Thread t = new Thread(...);
t.Start();
t.Sleep(1000); // Nope, Sleep is a static method

所有嵌套类型有效静态成员，因为您不能具有特定于包含类型实例的类型。

All nested types are effectively static members, in that you can't have a type which is specific to an instance of the containing type.

从C＃规范，第10.3.7节（强调我的）：

From the C# spec, section 10.3.7 (emphasis mine):

当字段，方法，属性，事件，操作符或构造函数声明包含一个 static 修饰符，它声明一个静态成员。 此外，常量或类型声明隐式声明一个静态成员。

When a field, method, property, event, operator or constructor declaration includes a static modifier, it declares a static member. In addition, a constant or type declaration implicitly declares a static member.

所以枚举是静态的该类型的成员，尽管没有 static 修饰符。

So the enum is a static member of the type, despite not having the static modifier.

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