在C ++中扩展枚举？ [英] Extending enums in C++?

问题描述

有没有方法在C ++中扩展/继承枚举？

Is there a way in C++ to extend/"inherit" enums?

IE：

enum Enum {A,B,C};
enum EnumEx : public Enum {D,E,F};

或至少定义它们之间的转换？

or at least define a conversion between them?

推荐答案

不，没有。

enum

即使是在C ++中引入的类枚举

Even the class enum introduced in C++0x does not address this extensibility issue (though they do some things for type safety at least).

枚举是它们不存在：它们提供某种类型的安全性，而不强加任何运行时开销，因为它们被编译器直接替换。

The only advantage of enum is that they do not exist: they offer some type safety while not imposing any runtime overhead as they are substituted by the compiler directly.

如果你想要这样的野兽，你必须自己工作：

If you want such a beast, you'll have to work yourself:

• 创建一个类 MyEnum 包含一个int（基本上）


• 为每个有趣的值创建命名构造函数

• create a class MyEnum, that contains an int (basically)
• create named constructors for each of the interesting values

现在可以扩展你的类（添加命名构造函数）在... ...

you may now extend your class (adding named constructors) at will...

这是一个解决方法，但我从来没有找到一个饱和的方式处理枚举...

That's a workaround though, I have never found a satistifying way of dealing with an enumeration...

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