以State Pattern取代巢狀迴圈

.NET   Design Pattern  

▌背景

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專案中需要判斷三次邏輯後，決定程式要執行的邏輯。 因此採用Design Pattern : State 來取代這些槽狀迴圈。

▌環境

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l   Windows 7 pro l   Visual Studio 2012 (C#)

▌實作

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▋State : Initiate

l   所有狀態的列舉型別

public enum TriggerActValStateEnum     {         Null = 1,         IamProfitAivCashIncludingLoss,         IamProfitAivCashPure,         IamProfitAivCntIncludingLoss,         IamProfitAivCntPure,         IamProfitAivRateIncludingLoss,         IamProfitAivRatePure     }

l   State interface

/// <summary> ///狀態interface /// </summary> public interface ITriggerActValState     {         /// <summary>         /// Trigger統計的方式         /// </summary>         TriggerActValStateEnum TriggerActValStateEnum { get; set; }         /// <summary>         ///  執行目前的狀態要做的事情，並設定下一個狀態         /// </summary>         void SetNewState(TriggerActValContext _context);     }

l   Create update codes for the Model

/// <summary> /// abstract class for 狀態 /// </summary> public abstract class TriggerActValState : ITriggerActValState     {         public TriggerActValStateEnum TriggerActValStateEnum { get; set; }         public abstract void SetNewState(TriggerActValContext context);     }

l   Context for state pattern

/// <summary> /// Context for state pattern /// </summary>     public class TriggerActValContext:IDisposable     {         /// <summary>         /// 目前的狀態類別         /// </summary>         public ITriggerActValState State {get;set;}         /// <summary>         /// 條件一         /// </summary>         public TriggerTypeEnum TriggerType { get; set; }         /// <summary>         /// 條件二         /// </summary>         public AIVTypeEnum AivType { get; set; }         /// <summary>         /// 條件三         /// </summary>         public bool IsIncludingOpposite { get; set; }         /// <summary>         /// Constructor         /// </summary>         /// <param name="triggerType">條件一</param>         /// <param name="aivType">條件二</param>         /// <param name="isIncludingOpposite">條件三</param>         public TriggerActValContext(             TriggerTypeEnum triggerType,             AIVTypeEnum aivType,             bool isIncludingOpposite)         {             this.TriggerType = triggerType;             this.AivType = aivType;             this.IsIncludingOpposite = isIncludingOpposite;             switch(triggerType) //由判斷條件一決定下一個狀態             {                 case TriggerTypeEnum.Profit:                     this.State = new IamProfitTrigger();                     break;                 case TriggerTypeEnum.Loss:                     this.State = new IamLossTrigger();                     break;                 default:                     break;             }         }         /// <summary>         /// 執行State裡面的動作         /// </summary>         public void EnableState()         {             this.State.SetNewState(this);         }     }

▋State : Implement Every State

l   判斷條件二決定下一個狀態

public class IamProfitTrigger : TriggerActValState     {                 public override void SetNewState(TriggerActValContext context)         { //設定目前狀態             base.TriggerActValStateEnum = TriggerActValStateEnum.Null;             //設定下一個工作             switch(context.AivType)             {                 case AIVTypeEnum.Cash:                     context.State = new IamProfitAivCash();                     break;                 case AIVTypeEnum.Counter:                     context.State = new IamProfitAivCnt();                     break;                 case AIVTypeEnum.Rate:                     context.State = new IamProfitAivRate();                     break;                 default:                     break;             }             context.EnableState();                     }     }

l   判斷條件三決定下一個狀態

public class IamProfitAivCnt : TriggerActValState     {         public override void SetNewState(TriggerActValContext context)         {             //設定目前狀態             base.TriggerActValStateEnum = TriggerActValStateEnum.Null;             //設定下一個工作             if (context.IsIncludingOpposite)             {                 context.State = new IamProfitAivCntIncludingLoss();             }             else             {                 context.State = new IamProfitAivCntPure();             }             context.EnableState();         }     }

l   決定最後的狀態

public class IamProfitAivCashIncludingLoss : TriggerActValState     {         public override void SetNewState(TriggerActValContext context)         {             //設定目前狀態             base.TriggerActValStateEnum = TriggerActValStateEnum.IamProfitAivCashIncludingLoss;         }     }

▋主程式

using (var context = new TriggerActValContext(triggerType, aivType, isIncludingLoss)) { context.EnableState(); //依據最後的狀態，決定要執行的邏輯     switch (context.State.TriggerActValStateEnum)     { case TriggerActValStateEnum.IamProfitAivCntPure:          //執行邏輯              break;          case TriggerActValStateEnum.IamProfitAivCashPure:          //執行邏輯              break;          //…          default:              break;      } }

▋Reference

l   The object cannot be deleted because it was not found in the ObjectStateManager