在switch语句中针对枚举进行编程,这是你的方法吗？

Question

看一下代码片段:

这是我在编写枚举时通常所做的事情.我有一个带有InvalidOperationException的默认转义(我不使用ArgumentException或它的一个派生,因为编码是针对私有实例字段而不是传入参数).

我想知道你们的开发人员是否也编写了这个逃避的想法....

public enum DrivingState {Neutral, Drive, Parking, Reverse};

public class MyHelper
{
    private DrivingState drivingState = DrivingState.Neutral;

    public void Run()
    {
        switch (this.drivingState)
        {
            case DrivingState.Neutral:
                DoNeutral();
                break;
            case DrivingState.Drive:
                DoDrive();
                break;
            case DrivingState.Parking:
                DoPark();
                break;
            case DrivingState.Reverse:
                DoReverse();
                break;
            default:
                throw new InvalidOperationException(
                    string.Format(CultureInfo.CurrentCulture, 
                    "Drivestate {0} is an unknown state", this.drivingState));
        }
    }
}

在代码审查中,我遇到了许多在默认转义中只有break语句的实现.这可能是一个问题随着时间的推移....

Answer 1

你的问题有点模糊,但据我所知,你问我们你的编码风格是否合适.我通常根据它的可读性来判断编码风格.

我读了一次代码,我明白了.所以,在我看来,你的代码是良好编码风格的一个例子.

Answer 2

有一个替代方案,就是使用与Java的枚举类似的东西.私有嵌套类型允许"更严格"的枚举,其中编译时唯一可用的"无效"值是null.这是一个例子:

using System;

public abstract class DrivingState
{
    public static readonly DrivingState Neutral = new NeutralState();
    public static readonly DrivingState Drive = new DriveState();
    public static readonly DrivingState Parking = new ParkingState();
    public static readonly DrivingState Reverse = new ReverseState();

    // Only nested classes can derive from this
    private DrivingState() {}

    public abstract void Go();

    private class NeutralState : DrivingState
    {
        public override void Go()
        {
            Console.WriteLine("Not going anywhere...");
        }
    }

    private class DriveState : DrivingState
    {
        public override void Go()
        {
            Console.WriteLine("Cruising...");
        }
    }

    private class ParkingState : DrivingState
    {
        public override void Go()
        {
            Console.WriteLine("Can't drive with the handbrake on...");
        }
    }

    private class ReverseState : DrivingState
    {
        public override void Go()
        {
            Console.WriteLine("Watch out behind me!");
        }
    }
}

Answer 3

我不喜欢这种方法,因为默认情况是不可测试的.这导致你的单元测试的覆盖率降低,虽然不一定是世界的末日,但是使我厌倦了强迫症.

我宁愿简单地对每个案例进行单元测试,并且还有一个额外的断言,即只有四种可能的情况.如果有人添加了新的枚举值,单元测试就会中断.

就像是

[Test]
public void ShouldOnlyHaveFourStates()
{
    Assert.That(Enum.GetValues( typeof( DrivingState) ).Length == 4, "Update unit tests for your new DrivingState!!!");
}