如何獲得無狀態框架的優勢

Question

我想在我的代碼中使用http://code.google.com/p/stateless來將功能從它的依賴關係中分離出來。我沒有找到任何用法的高級示例，所以這個問題是關於無狀態框架最佳實踐的。

我具有以下結構（這只是例子，僅具有一個功能狀態）：

var stateMachine = new StateMachine(State.Stopped); 

stateMachine.Configure(State.Stopped) 
    .Permit(Trigger.Failed, State.Error) 
    .Permit(Trigger.Succeed, State.GenerateMachineData); 

stateMachine.Configure(State.GenerateMachineData) 
    .Permit(Trigger.Failed, State.Error) 
    .Permit(Trigger.Succeed, State.Finished); 

public enum State 
{ 
    Stopped, 
    GenerateMachineData, 
    Finished, 
    Error 
} 

public enum Trigger 
{ 
    Succeed, 
    Failed 
} 

其中調用實際功能即可。我下面的想法，但他們每個人都有優點和缺點：

1）設置功能以及未來火OnEntry（）：

stateMachine.Configure(State.GenerateMachineData) 
.OnEntry(() => { 
    try { 
     Generate(); 
     stateMachine.Fire(Trigger.Succeed); 
    } catch { 
     stateMachine.Fire(Trigger.Error); 
    } 
}) 
.Permit(Trigger.Failed, State.Error) 
.Permit(Trigger.Succeed, State.Finished); 

這樣的話，如果我只是叫

stateMachine.Fire(Trigger.Succeed); 

它結束了無論是在State.Finished或State.Error

• 優點 - 所有一起
• disadvatages - 溶液不能得到真正unittested

2）具有的statemachine和功能分離，如：

 
void DoTheStuff() { 
    switch (stateMachine.State) 
    { 
     State.Stopped: 
       stateMachine.Fire(State.Succeed); 
       break; 
     State.GenerateMachineData: 
       Generate(); 
       stateMachine.Fire(State.Succeed); 
       break; 
     default: 
       throw new Exception(); 
    } 
}
 

void Main() { while (stateMachine.State != State.Succeed && stateMachine.State != State.Error) { DoTheStuff(); } } 

• advantages: the statemachine can be tested itself
• disadvantages: I quite don't like it

3) some other solution?

I will be glad for any answer

Answer 1

I like BugTrackerExample which they have in source code.

So your machine would probably look like this:

class Generator 
{ 
    private readonly StateMachine state; 

    public Generator() 
    { 
     state = new StateMachine(State.Stopped); 

     // your definition of states ... 

     state.Configure(State.GenerateMachineData) 
     .OnEntry(() => { Generate(); }) 
     .Permit(Trigger.Failed, State.Error) 
     .Permit(Trigger.Succeed, State.Finished); 

     // ... 
    } 

    public void Succeed() 
    { 
     state.Fire(Trigger.Succeed); 
    } 

    public void Fail() 
    { 
     state.Fire(Trigger.Fail); 
    } 

    public void Generate() 
    { 
     // ...   
    } 
} 

In this case tests shouldn't be problem.

If you need further separation you can use event, delegate or strategy pattern instead of Generate方法。

Answer 2

Nicholas Blumhardt寫了關於無狀態框架的good post。