If—Else \ If-ElseIf—Else 的隨想、改造

最近有一個想法，想把這些If--Else、If-ElseIf-Else，全部換成一條條的Command,然後把這個Command串起來，最後放到CommandList中把它們一鍋端了。:)

所以以下就這個想法產物：

先列舉一下通常的分支、支叉

static String IfElseIfElse (Int32 conditionParam) {
            var result = String.Empty;
            if ( conditionParam == 1 ) {
                result = "conditionParam1";
            }
            else if ( conditionParam == 2 ) {
                result = "conditionParam2";
            }
            else {
                result = "default";
            }
            return result;
        }

那現在就按照想法、分不同情境來進化Code吧

情境1：根據傳統的If-Else進行的改造，只適用傳統的True Or Else的操作

聲明方法： T ExecuteCommand<T> (IDictionary<Boolean , List<Func<T>>> commandList)

具體代碼：

          /// <summary>
       /// 適用傳統的True Or False的操作
       /// </summary>
       static T ExecuteCommand<T> (IDictionary<Boolean , List<Func<T>>> commandList) {
           T t = default ( T );
           foreach ( var command in commandList ) {
               if ( command.Key ) {
                   t = command.Value[0] ();
                   break;
               }
               else {
                   t = command.Value[1] ();
                   break;
               }
           }
           return t;
       }

具體應用：

            /// <summary>
      /// 根據傳統的If-Else進行的改造
      /// </summary>
      static String CommandList (Int32 conditionParam) {

          var commandList = new Dictionary<Boolean , List<Func<String>>> ();
          {
              commandList.Add ( ( conditionParam == 1 ) ,
                                  new List<Func<String>> (){
                                  ()=> { return  "conditionParam1"; },
                                  ()=> { return "-conditionParam1"; }
                              } );
              commandList.Add ( ( conditionParam == 2 ) ,
                                  new List<Func<String>> () {
                                  ()=> { return "conditionParam2"; }
                              } );
          }
          return ExecuteCommand<String> ( commandList );
      }

--------------------------------------------------------------------------------------------------------------------------------------------------

情境2：根據“情境1”缺點，增加了對If-ElseIf-Else的支援

聲明方法： T ExecuteCommand<T> (Boolean? condition , Func<T> action)

具體代碼：

          /// <summary>
       /// 適用True And False And Default的操作
       /// </summary>
       static T ExecuteCommand<T> (Boolean? condition , Func<T> action) {
           T t = default ( T );
           if ( condition.HasValue ) {
               if ( condition.Value ) { t = action (); }
           }
           else {
               t = action ();
           }
           return t;
       }

具體應用：

             /// <summary>
       /// 增加了對If-ElseIf-Else的支援
       /// </summary>
       static String CommandFuncList (Int32 conditionParam) {
           var commandList = new List<String> (){
            ExecuteCommand<String>(( conditionParam ==1 ),
                                   ()=> { return  "conditionParam1"; }
            ),
            ExecuteCommand<String>(( conditionParam ==2 ),
                                   ()=> { return "conditionParam2"; }
            ),
            ExecuteCommand<String>(null,
                                   ()=> { return "default"; }
            )
           };
           return commandList.Where ( o => o != null ).First ();
       }

--------------------------------------------------------------------------------------------------------------------------------------------------

以上情境都是帶傳回值，那如何對不同分支、不同那個什麼；只想執行方法，一個方法或多個方法，又應該如何處理呢？

情境3：告訴我們還可以這樣幹

聲明方法：List<Action> ExecuteCommand (Boolean? condition , List<Action> action)

具體方法：

             /// <summary>
       /// 只適用If-Else的方法操作
       /// </summary>
       static List<Action> ExecuteCommand (Boolean? condition , List<Action> action) {
           List<Action> _action = default ( List<Action> );
           if ( condition.HasValue ) {
               if ( condition.Value ) {
                   _action = action;
               }
           }
           else {
               _action = action;
           }
           return _action;
       }

具體應用：

       static void CommandActionList (Int32 conditionParam) {
            var commandList = new List<List<Action>> (){
             ExecuteCommand(( conditionParam ==1 ),
                            new List<Action>() { ()=> Write() }
             ),
             ExecuteCommand(( conditionParam ==2 ),
                            new List<Action>(){
                                  ()=> Write(),
                                  ()=> WriteAction()
                            }
             )
            };
            commandList.Where ( o => o != null ).Select ( o => o ).ToList ().ForEach ( o => o.ForEach ( i => i () ) );
        }

--------------------------------------------------------------------------------------------------------------------------------------------------

情境4：告訴我們，加上執行步驟，會讓我們對分支掌控遊刃有餘

聲明方法：List<Action> ExecuteCommand (ref Boolean execStep , Boolean? condition , List<Action> action)

具體方法：

          static List<Action> ExecuteCommand (ref Boolean execStep , Boolean? condition , List<Action> action) {
            List<Action> _action = default ( List<Action> );
            if ( execStep ) {
                if ( condition.HasValue ) {
                    if ( condition.Value ) {
                        _action = action;
                        execStep = false;
                    }

                }
                else {
                    _action = action;
                    execStep = false;
                }
            }
            return _action;
        }

具體應用：

       static void CommandActionListWithStep (Int32 conditionParam) {
            var execStep = true;
            var commandList = new List<List<Action>> (){
             ExecuteCommand(ref execStep,( conditionParam ==1 ),
                            new List<Action>() { ()=> Write() }
             ),
             ExecuteCommand(ref execStep,( conditionParam ==2 ),
                            new List<Action>(){
                                  ()=> Write(),
                                  ()=> WriteAction()
                            }
             ),
             ExecuteCommand(ref execStep,null, new List<Action>(){ ()=> WriteDefault() } )
            };

            commandList.FindAll ( (p) => { return p != null; } )
                       .ForEach ( o => o.ForEach ( i => i () ) );
        }

 

        static void Write () { Console.Write ( "Hello Command" ); }

        static void WriteAction () { Console.Write ( "Hello Action" ); }

        static void WriteDefault () { Console.Write ( "Hello Default" ); }

--------------------------------------------------------------------------------------------------------------------------------------------------

最終全部方法執行結果：

static void Main (string[] args) {
           Console.Write ( "IfElseIfElse ( 1 )" + IfElseIfElse ( 1 ) );
           Console.WriteLine ();
           Console.Write ( "IfElseIfElse ( 4 )" + IfElseIfElse ( 4 ) );
           Console.WriteLine ();
           Console.Write ( "CommandList ( 1 )" + CommandList ( 1 ) );
           Console.WriteLine ();
           Console.Write ( "CommandList ( 2 )" + CommandList ( 2 ) );
           Console.WriteLine ();
           Console.Write ( "CommandFuncList ( 1 )" + CommandFuncList ( 1 ) );
           Console.WriteLine ();
           Console.Write ( "CommandFuncList ( 4 )" + CommandFuncList ( 4 ) );
           Console.WriteLine ();
           CommandActionList ( 1 );
           Console.WriteLine ();
           CommandActionList ( 2 );
           Console.WriteLine ();
           CommandActionListWithStep ( 1 );
           Console.WriteLine ();
           CommandActionListWithStep ( 4 );
           Console.WriteLine ();
       }