C# 泛型或反射 - 调用未知类的函数

Question

我正在制作一款游戏，其中工作人员根据当前的任务 执行操作。每个 worker 都将按照首选顺序(受玩家决定的影响)分配一份任务列表。

当一项任务完成时(例如，将元素从 X 拿到 Y)，工作人员需要通过检查可能的任务列表来开始一项新任务，看看是否可以执行每项任务，如果可以，则设置他们的当前任务到该任务并启动它(最后一个任务 - “Wander Around”始终可用)。

我目前使用一个大的 switch 语句和枚举来完成这项工作，但现在想概括这段代码以创建一个 Task 类，并为工作人员提供一个首选任务列表，一个 GetNextTask() 函数，并在 worker 的 Update() 方法中调用 currentTask.update()(这将使 worker 执行他需要的任何操作在当前任务下执行，并在任务完成时调用 worker.GetNextTask()。

我不清楚的是在 worker 中存储任务的最佳方式。我应该使用:

1) 反射(reflection)。将可能的任务存储为类型列表，然后使用反射来 a) 调用静态方法 public static virtual bool CanPerformThisTask()，它在每个子类中被覆盖，以及 b) 创建该任务的实例为 worker ？(下面的示例代码尝试 - 但无法测试)

2) 每当工作人员需要获得新任务(可能使用 Activator)时实例化所有任务，并检查每个任务的 (Task)task.CanPerformThisTask() - 如果为真，则执行此操作任务。不过，将它们全部实例化似乎效率很低？

3) 泛型。这可以使用泛型来完成吗？如果是，怎么办？

这是我类(class)的一个片段，用于说明我正在尝试做的事情:

worker 类(Class):

protected List<Point> waypoints = new List<Point>();
public bool reachedDestination { get { return waypoints.Count == 0; } }
protected Task task;
public List<Type> possibleTasks;

public Worker(Task initialTask, List<Type> initialPossibleTasks ...)
: base(...)
{
     task = initialTask;
     possibleTasks = initialPossibleTasks;
}

public override void Update()
{
     base.Update();
     if (!reachedDestination) Move();
     task.Update();
}

public void GetNextTask()
{
    foreach (Type t in possibleTasks)
    {
        //reflection code here - will this work and can we do this with generics instead?
        Bool canDoT = (bool)t.GetMethod("CanPerformThisTask", BindingFlags.Static | BindingFlags.Public).Invoke(null, null);
        if (canDoT)
        {
            task = Activator.CreateInstance(t);
            return;
        }
    }
}

这是我的 Task 基类的一些不完整代码(不应实例化):

public class Task
{
    public Worker worker;

    public virtual static bool CanPerformThisTask()
    {
        //never call this from here - always from subclasses
        return false;
    }

    public Task()
    {
        //set up code here
    }

    public virtual void Update()
    {
        //make worker do relevant activities here
        //call finish task when done
    }

    public void FinishTask()
    {
        worker.GetNextTask();
    }

}

这里是工作人员将在其可能任务列表中拥有的任务示例:

public class T_WorkerWander : Task
{

    public static override bool CanPerformThisTask()
    {
        //can always wander (other Tasks will have conditions here)
        return true;
    }

    public T_WorkerWander()
        : base()
    {
    }

    override public void Update()
    {
        //make the worker wander here
        if (worker.reachedDestination) FinishTask();
    }

}

---

更新:这是我现在可以使用的代码

任务类:

public abstract class Task
{
    //the entity holding this task
    public TaskableEntity taskEntity;

    public List<TaskStage> taskStages;
    public TaskStage currentTaskStage { get { return taskStages[0]; } }

    public Task(TaskableEntity t) { taskEntity = t; }

    /// <summary>
    /// the conditions for the Task to be started
    /// </summary>
    public virtual bool CanStart()
    {
        return true;
    }

    public void Start()
    {
        taskStages = new List<TaskStage>();
        InitialiseTaskStages();
        taskStages[0].Start();
    }

    public abstract void InitialiseTaskStages();

    public void Update()
    {
        currentTaskStage.Update();
        if (currentTaskStage.IsComplete()) TaskStageComplete();
    }

    public void TaskStageComplete()
    {
        taskStages.RemoveAt(0);
        if (taskStages.Count == 0) taskEntity.TaskComplete();
        else currentTaskStage.Start();
    }

    public void SetTaskStages(params TaskStage[] t)
    {
        taskStages = t.ToList();
    }

    public void Interrupt()
    {
        currentTaskStage.Interrupt();
    }

}

任务阶段类:

public sealed class TaskStage
{
    private Task task;

    private List<Point> pointsToMoveTo;
    public void SetPointsToMoveTo(Point p) { pointsToMoveTo = new List<Point>() { p }; }
    public void SetPointsToMoveTo(params Point[] p) { pointsToMoveTo = p.ToList(); }
    public void SetPointsToMoveTo(List<Point> p) { pointsToMoveTo = p; }
    public Action actionToApply;

    private float timeToWait;
    public void SetWait(float wait) { timeToWait = wait; }

    private IReservable[] itemsToReserve;
    public void SetItemsToReserve(params IReservable[] items) { itemsToReserve = items; }

    private IReservable[] itemsToUnreserve;
    public void SetItemsToUnreserve(params IReservable[] items) { itemsToUnreserve = items; }

    private Emotion emotionToSet;
    public void SetEmotionToSet(Emotion e) { emotionToSet = e; }

    private TaskStage _interrupt;
    public void SetInterruptAction(TaskStage t) { _interrupt = t; }
    public void Interrupt() { _interrupt.Start(); }

    public TaskStage(Task t)
    {
        task = t;
    }

    public void Start()
    {
        if (actionToApply != null) actionToApply();
        if (itemsToUnreserve != null) UnreserveItems();
        if (itemsToReserve != null) ReserveItems();
        if (pointsToMoveTo != null)
        {
            //this will need changing after pathfinding sorted out...
            if (pointsToMoveTo.Count == 1) task.taskEntity.SetWaypoints(pointsToMoveTo[0]);
            else task.taskEntity.waypoints = pointsToMoveTo;
        }
        if (emotionToSet != null) emotionToSet.StartEmotion();
    }

    public void Update()
    {
        if (timeToWait > 0) timeToWait -= GV.elapsedTime;
    }

    public bool IsComplete()
    {
        if (pointsToMoveTo != null && !task.taskEntity.reachedDestination) return false;
        if (timeToWait > 0) return false;
        return true;
    }

    public void ReserveItems()
    {
        foreach (IReservable i in itemsToReserve)
        {
            i.reserved = true;
        }
    }

    public void UnreserveItems()
    {
        foreach (IReservable i in itemsToUnreserve)
        {
            i.reserved = false;
        }
    }

}

示例任务:

public class T_WorkerGoToBed : Task
{
    public FactoryWorker worker { get { return taskEntity as FactoryWorker; } }
    public T_WorkerGoToBed(TaskableEntity t)
        : base(t) { }

    public override bool CanStart()
    {
        return Room.Available<Bed>(GV.Bedrooms);
    }

    public override void InitialiseTaskStages()
    {
        Bed bedToSleepIn = Room.NearestAvailableFurniture<Bed>(GV.Bedrooms, taskEntity.X, taskEntity.Y);

        //stage 1 - reserve bed and move there
        TaskStage ts1 = new TaskStage(this);
        ts1.SetItemsToReserve(bedToSleepIn);
        ts1.SetPointsToMoveTo(bedToSleepIn.XY);

        //stage 2 - sleep in bed
        TaskStage ts2 = new TaskStage(this);
        ts2.SetWait((worker.maxEnergy - worker.energy) / worker.energyRegeneratedPerSecondWhenSleeping);
        ts2.SetEmotionToSet(new E_Sleeping(worker, false));

        //stage 3 - unreserve bed
        TaskStage ts3 = new TaskStage(this);
        ts3.SetItemsToUnreserve(bedToSleepIn);
        ts3.SetEmotionToSet(new E_Happy(worker, false));

        SetTaskStages(ts1, ts2, ts3);
    }

}

Answer 1

听起来您需要颠倒任务和工作人员之间的职责。与其询问是否可以执行任务，不如询问 worker 是否可以执行给定的任务:

class Worker
{
    bool CanPerformTask<T>() where T : Task
    {
        var type = typeof(T);
        // code to determine whether worker can perform the task T             
    }

    // alternative with instance parameter
    bool CanPerformTask<T>( T task ) where T : Task
    {
        // code to determine whether worker can perform the task passed in
    }
}

该方案避免了“实例化所有任务或调用静态方法”的问题。

此外，请考虑使用内置的集合类。队列和堆栈等事物可以极大地简化安排事物执行所需的代码。