我有一些相当简单的状态需求(目前)。我想我想使用 Stateless 对这些进行建模接口(interface)。 (但我对状态机了解不多，所以我可能是错的。)

但我对术语很感兴趣(特别是State 和Trigger)

这是一个例子:我有一个订单类。它设置有几个状态。它们是:新的、填充的、运输的、已完成的、已取消的。

我想要的一些简单状态规则是允许这些状态转换:

• 新建(默认)
• 新建 -> 填充
• 新建 -> 已取消
• 已填写 -> 发货
• 填写 -> 取消
• 填充 -> 运输
• 发货 -> 完成

那么我在这里被绊倒的地方是我的“触发器”是什么？

以防万一需要更具体的示例，假设我想要这样的方法:

public bool UpdateOrderStatus(int OrderId, OrderStatusEnum NewOrderStatus)

如果状态更新成功，将返回 true。如何设置和使用无状态来实现这一目标？

最佳答案

The machine is in only one state at a time; the state it is in at any given time is called the current state. It can change from one state to another when initiated by a triggering event or condition, this is called a transition. from Finite-state machine on Wiki

我相信，触发器就是这个触发事件。

更新:

当然触发器名称有时可以等于某些状态名称。

New (initial state)
New -> Filled (trigger "Filled")
New -> Cancelled (trigger "Cancelled")
Filled -> Shipping (trigger "ToBeShipped")
Filled -> Cancelled (trigger "Cancelled")
Shipping -> Complete (trigger "Completed").

更新:

stateless 是非常好的框架! 我已尝试实现该功能。

状态:

public enum State
{
    New,
    Filled,
    Shipping,
    Cancelled,
    Completed
}

触发器:

public enum Trigger
{
    Filled,
    Cancelled,
    ToBeShipped,
    Completed
}

订单类:

public class Order
{
    private readonly StateMachine<State, Trigger> _stateMachine;

    public Order()
    {
        _stateMachine = CreateStateMachine();
    }

    public bool TryUpdateOrderStatus(Trigger trigger)
    {
        if (!_stateMachine.CanFire(trigger))
            return false;

        _stateMachine.Fire(trigger);
        return true;
    }

    public State Status
    {
        get
        {
            return _stateMachine.State;
        }
    }

    private StateMachine<State, Trigger> CreateStateMachine()
    {
        StateMachine<State, Trigger> stateMachine = new StateMachine<State, Trigger>(State.New);
        stateMachine.Configure(State.New)
            .Permit(Trigger.Filled, State.Filled)
            .Permit(Trigger.Cancelled, State.Cancelled);

        stateMachine.Configure(State.Filled)
            .Permit(Trigger.ToBeShipped, State.Shipping)
            .Permit(Trigger.Cancelled, State.Cancelled);

        stateMachine.Configure(State.Shipping)
            .Permit(Trigger.Completed, State.Completed);

        stateMachine.OnUnhandledTrigger((state, trigger) =>
            {
                Console.WriteLine("Unhandled: '{0}' state, '{1}' trigger!");
            });
        return stateMachine;
    }
}

订单类测试人员:

Order order = new Order();
bool result = order.TryUpdateOrderStatus(Trigger.Completed);
Console.WriteLine("Attemp to complete order: {0}", result);
Console.WriteLine("Order status: {0}", order.Status);

result = order.TryUpdateOrderStatus(Trigger.ToBeShipped);
Console.WriteLine("Attemp to ship order: {0}", result);
Console.WriteLine("Order status: {0}", order.Status);

result = order.TryUpdateOrderStatus(Trigger.Cancelled);
Console.WriteLine("Attemp to cancel order: {0}", result);
Console.WriteLine("Order status: {0}", order.Status);

关于c# - 使用无状态的基本状态机设置，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/9117487/