C# 可选输出参数

Question

有什么方法可以使方法的输出参数可选？我有一个方法需要几个参数大部分时间返回 null，但有时它们会有一个值。我试图找出是否有比先将值设置为 null 或在 if/else 之后将它们设置为 null 更好的方法来完成此操作。这可能是唯一的方法，但如果有可选的输出参数或类似的东西就更好了。这是代码:

    private static void GetInitInfo(string initLine, string ncPointType, out double? relinquishDefault, out bool? ignoreRelinquishDefault, out bool? closedForStart, out bool? adjustDisabled)
    {
        relinquishDefault = null;
        ignoreRelinquishDefault = null;
        closedForStart = null;
        adjustDisabled = null;

        switch (ncPointType)
        {
            case "MSD":
                adjustDisabled = LastToken<bool?>(initLine);
                break;
            case "BO":
                relinquishDefault = SecondToken<double>(initLine);
                closedForStart = ThirdToken<bool?>(initLine);
                ignoreRelinquishDefault = !ForthToken<bool?>(initLine);//ignoreRelDef would be reverse of use initial value
                break;
            case "MSO":
                closedForStart = SecondToken<bool?>(initLine);
                relinquishDefault = ThirdToken<double>(initLine);
                ignoreRelinquishDefault = !ForthToken<bool?>(initLine);//ignoreRelDef would be reverse of use initial value
                break;
            case "AD":
                relinquishDefault = ThirdToken<double>(initLine);
                ignoreRelinquishDefault = false;
                break;
            case "BD":
                relinquishDefault = SecondToken<double>(initLine);
                adjustDisabled = LastToken<bool?>(initLine);
                ignoreRelinquishDefault = false;
                break;
            case "AOS":
                relinquishDefault = FirstToken<double>(initLine);
                ignoreRelinquishDefault = !ThirdToken<bool?>(initLine);//ignoreRelDef would be reverse of use initial value
                break;
        }
    }

Answer 1

根据 C# 4.0 规范:第 21.1 节，这是不允许的。

解决方法是使用另一个没有 out 或 ref 参数的方法重载。