如何将常量与C＃中的接口相关联？ [英] How to associate constants with an interface in C#?

问题描述

有些语言允许您将常数与界面相关联：

Some languages let you associate a constant with an interface:

• Java示例


• PhP示例

• A Java example
• A PhP example

W3C抽象界面也是这样做的，例如：

The W3C abstract interfaces do the same, for example:

// Introduced in DOM Level 2:
interface CSSValue {

  // UnitTypes
  const unsigned short      CSS_INHERIT                    = 0;
  const unsigned short      CSS_PRIMITIVE_VALUE            = 1;
  const unsigned short      CSS_VALUE_LIST                 = 2;
  const unsigned short      CSS_CUSTOM                     = 3;

  attribute DOMString       cssText;
  attribute unsigned short  cssValueType;
};

我想定义此接口，以便可以从C＃调用。

I want to define this interface such that it can be called from C#.

显然，C＃无法定义与接口关联的常量。

Apparently C# cannot define a constant associated with an interface.

• 虽然C＃不能，但是还有另一种.NET语言可以定义与接口相关的常量？

推荐答案

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To answer your third question:

虽然C＃不能，但是还有另一种.NET语言可以定义与接口相关的常量吗？

Although C# cannot, is there another .NET language which can define constants associated with an interface?

C ++ / CLI允许您在接口中定义 literal 值，这等价于 static const

C++/CLI allows you to define literal values in an interface, which are equivalent to static const values in C#.

public interface class ICSSValue
{
public:
    literal short CSS_INHERIT = 0;
    literal short CSS_PRIMITIVE_VALUE = 1;
    literal short CSS_VALUE_LIST = 2;
    literal short CSS_CSS_CUSTOM = 3;

    property DOMString^ cssText;
    property ushort cssValueType;
}

然后，您可以通过C＃访问这些值：

You could then access the values via C#:

public static void Main()
{
    short primitiveValue = ICSSValue.CSS_PRIMITIVE_VALUE;

    Debug.Assert(primitiveValue == 1);
}

查看更多详情请参阅MSDN上的此页面。

See this page on MSDN for more details.

免责声明：
设计决定禁止接口中的常量值是一个很好的选择。暴露实现细节的接口很可能是泄漏抽象。在这个例子中CSS值类型可能更好一个枚举。

Disclaimer: The design decision to disallow constant values in interfaces was a good one. An interface which exposes implementation details is most likely a leaky abstraction. In this example CSS Value Type is probably better off being an enumeration.

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