c# - 我如何在类型安全的枚举模式上使用 switch 语句

Question

我以不同的方式找到了一个关于实现枚举的漂亮示例。我认为这就是所谓的类型安全枚举模式。我开始使用它，但我意识到我不能在 switch 语句中使用它。
我的实现如下所示:

public sealed class MyState
{
    private readonly string m_Name;
    private readonly int m_Value;

    public static readonly MyState PASSED= new MyState(1, "OK");
    public static readonly MyState FAILED= new MyState(2, "ERROR");

    private MyState(int value, string name)
    {
        m_Name = name;
        m_Value = value;
    }

    public override string ToString()
    {
        return m_Name;
    }

    public int GetIntValue()
    {
        return m_Value;
    }
}

为了能够在 C# 的 switch 语句中使用此模式，我可以向我的类中添加什么？
谢谢。

Answer 1

你可以尝试这样的事情:

class Program
{
    static void Main(string[] args)
    {
        Gender gender = Gender.Unknown;

        switch (gender)
        {
            case Gender.Enum.Male:
                break;
            case Gender.Enum.Female:
                break;
            case Gender.Enum.Unknown:
                break;
        }
    }
}

public class Gender : NameValue
{
    private Gender(int value, string name)
        : base(value, name)
    {
    }

    public static readonly Gender Unknown = new Gender(Enum.Unknown, "Unknown");
    public static readonly Gender Male = new Gender(Enum.Male, "Male");
    public static readonly Gender Female = new Gender(Enum.Female, "Female");
    public class Enum
    {
        public const int Unknown = -1;
        public const int Male = 1;
        public const int Female = 2;
    }

}

public abstract class NameValue
{
    private readonly int _value;
    private readonly string _name;

    protected NameValue(int value, string name)
    {
        _value = value;
        _name = name;
    }

    public int Value
    {
        get { return _value; }
    }

    public string Name
    {
        get { return _name; }
    }

    public override string ToString()
    {
        return Name;
    }
    public override int GetHashCode()
    {
        return Value.GetHashCode();
    }

    public override bool Equals(object obj)
    {
        NameValue other = obj as NameValue;
        if (ReferenceEquals(other, null)) return false;
        return this.Value == other.Value;
    }

    public static implicit operator int(NameValue nameValue)
    {
        return nameValue.Value;
    }
}