尝试类型安全，枚举模式

public sealed class AuthenticationMethod {

    private readonly String name;
    private readonly int value;

    public static readonly AuthenticationMethod FORMS = new AuthenticationMethod (1, "FORMS");
    public static readonly AuthenticationMethod WINDOWSAUTHENTICATION = new AuthenticationMethod (2, "WINDOWS");
    public static readonly AuthenticationMethod SINGLESIGNON = new AuthenticationMethod (3, "SSN");        

    private AuthenticationMethod(int value, String name){
        this.name = name;
        this.value = value;
    }

    public override String ToString(){
        return name;
    }

}

更新
显式（或隐式）类型转换可以通过

Update Explicit (or implicit) type conversion can be done by

• 添加静态字段映射

• adding static field with mapping

private static readonly Dictionary<string, AuthenticationMethod> instance = new Dictionary<string,AuthenticationMethod>();

• n.b。为了在调用构造函数时的枚举成员字段的初始化没有抛出一个NullReferenceException，一定要把字典前场在你的类中的枚举成员字段。这是因为静态字段initialisers被称为声明顺序和静态构造函数之前，创建怪异的和必要的，但混乱的局面，所有的静态字段都被初始化前的实例构造函数可以调用，静态构造函数被调用之前。



在实例构造填补这一映射

filling this mapping in instance constructor

instance[name] = this;

public static explicit operator AuthenticationMethod(string str)
{
    AuthenticationMethod result;
    if (instance.TryGetValue(str, out result))
        return result;
    else
        throw new InvalidCastException();
}