Interface笔记

Abstract的问题：

Abstract也许看上去优美，有一般methrod，virtual methord，或者abstract metho

 1  abstract class Car
 2     {
 3         abstract public void tALK();
 4         public void Drive()
 5         {
 6             Console.WriteLine("WROOOOOOM");
 7         }
 8         public virtual void TruboBosst()
 9         {
10             Console.WriteLine("Styuff and things!");
11         }
12     }

有问题，首先you can't inherate from more than one type，其次这样的规则形成了父类可能要写很长，并且make some changes will break all inherate class.问题三，继承存在冲突，看下面示例，如果一辆车即是可以移动又要可以买怎么办？

View Code

 1 abstract class Purchasedable
 2     {
 3 
 4     }
 5     abstract class Moveable
 6     {
 7 
 8     }
 9     abstract class Car
10     {
11         abstract public void tALK();
12         public void Drive()
13         {
14             Console.WriteLine("WROOOOOOM");
15         }
16         public virtual void TruboBosst()
17         {
18             Console.WriteLine("Styuff and things!");
19         }
20     }

再比如椅子的例子

View Code

 1 abstract class Purchasedable
 2     {
 3 
 4     }
 5     abstract class Moveable : Purchasedable
 6     {
 7 
 8     }
 9     abstract class Car : Moveable
10     {
11         abstract public void Talk();
12         public void Drive()
13         {
14             Console.WriteLine("WROOOOOOM");
15         }
16         public virtual void TruboBosst()
17         {
18             Console.WriteLine("Styuff and things!");
19         }
20     }
21     class Chair : Moveable
22     {
23         //所有的chair都要是可以一定的，但并不需要所有多有价钱，这样就有问题了
24     }
25     class Menu : Purchasedable
26     {
27 
28     }
29     class Car1 : Car
30     {
31         public override void Talk()
32         {
33 
34         }
35     }

可以abstract和interface同时使用，因为abstract可以有common methord在里面，所以abstract可以继承多个interface（想成可以连接任意多个abstract），然后再写入要re-use的 methord，这样继承这个abstract就同时有了两个优点

理解：

interface can not have implementation in it
interface have no excutable code in it
名字加I
比abstract更小，只有定义

interface可以放property，methord，event, 不可以有field

View Code

1 interface IMoveable
2     {
3         void Move();
4     }
5     interface IBuyable
6     {
7         decimal Price { get; }
8         void Buy();
9     }

所有的member都是abstract的，所有的一切（包括内部定义的setter）都是public的。member的访问类型可以不加默认是Public的，内部的setter也可以不加，但是要注意继承类都要加回去。有一个问题继承类的实现部分要是private的setter，interface里不要写set关键字，所以记住interface里的property最好setter都不写

View Code

 1 interface IMoveable
 2     {
 3         void Move();
 4     }
 5     interface IBuyable
 6     {
 7         decimal Price { get; }  //不写关键字
 8         void Buy();
 9     }
10     class Car : IMoveable, IBuyable
11     {
12         public Car( decimal price)
13         {
14             Price = price;
15         }
16         public decimal Price { get; private set; }
17 
18         public void Move()
19         {
20             Console.WriteLine("This car can move");
21         }
22 
23         public void Buy()
24         {
25             Console.WriteLine("I buy this car, using ${0}", Price);
26         }

把abstract关键字去掉，把访问类型关键字去掉，并且去掉field和具体的implementation就成了interface了

继承interface的类的实现（继承类只能是public的（默认可以不用写），不可以是private或者protect的）

View Code

 1 class Car : IMoveable, IBuyable
 2     {
 3         public Car( decimal price)
 4         {
 5             Price = price;
 6         }
 7         public decimal Price { get; private set; }
 8 
 9         public void Move()
10         {
11             Console.WriteLine("This car can move");
12         }
13 
14         public void Buy()
15         {
16             Console.WriteLine("I buy this car, using ${0}", Price);
17         }
18     }

区分interface inherate，class inherate, class inherate interface

实例1：解决有共同type交集的collection在runtime下还含有各自不同type的问题

View Code

  1 using System;
  2 using System.Collections.Generic;
  3 using System.Linq;
  4 using System.Text;
  5 
  6 namespace ConsoleApplication6
  7 {
  8     interface IItem
  9     {
 10         string Name { get; }
 11     }
 12     interface IMoveable
 13     {
 14         void Move();
 15     }
 16     interface IBuyable
 17     {
 18         decimal Price { get; } 
 19         void Buy();
 20     }
 21     class Car : IItem, IMoveable, IBuyable
 22     {
 23         
 24         public decimal Price { get; private set; }
 25         public string Name { get; private set; }
 26         public Car(string name, decimal price)
 27         {
 28             Price = price;
 29             Name = name;
 30         }
 31 
 32         public void Move()
 33         {
 34             Console.WriteLine("This car can move");
 35         }
 36 
 37         public void Buy()
 38         {
 39             Console.WriteLine("I buy this car, using ${0}", Price);
 40         }
 41     }
 42     class Chair : IItem, IMoveable
 43     {
 44 
 45         public string Name
 46         {
 47             get;
 48             private set;
 49         }
 50         public Chair(string name)
 51         {
 52             Name = name;
 53         }
 54         public void Move()
 55         {
 56             Console.WriteLine("Moving the chair {0}", Name);
 57         }
 58     }
 59     class Program
 60     {
 61         static void Main(string[] args)
 62         {
 63             var items = new List<IItem>();
 64             items.Add(new Car("Small Truck", 32.45m));
 65             items.Add(new Chair("Golden Chair"));
 66             items.Add(new Car("Big Coco", 123.99m));
 67             items.Add(new Car("Luxary Dip", 41.5511m));
 68             items.Add(new Chair("Funny Chair"));
 69 
 70             while(true)
 71             {
 72                 
 73 
 74                 
 75 
 76                 var chosenItem = ChooseItem(items);
 77                 var moveable = chosenItem as IMoveable;
 78                 var buyable = chosenItem as IBuyable;
 79                 Console.WriteLine("What you want me to do?");
 80 
 81                 var input = Console.ReadLine();
 82                 if (buyable != null && input == "buy")
 83                 {
 84                     buyable.Buy();
 85                 }
 86                 else if (moveable != null && input == "move")
 87                 {
 88                     moveable.Move();
 89                 }
 90                 else
 91                 {
 92                     Console.WriteLine("Invalid");
 93                 }
 94     
 95             }
 96 
 97             Console.ReadLine();
 98         }
 99 
100         static IItem ChooseItem(List<IItem> items)
101         {
102             while (true)
103             {
104                 var index = 1;
105                 foreach (var item in items)
106                 {
107                     Console.Write("[{0}] - {1}", index, item.Name);
108                     
109                     //Iterface最重要的一点是可以换type，换方法集。
110                     //其实这里buyable和item指向的都是同一个对象
111                     //根据assign的type不同便可以assign不同member
112                     //其实每个item是更具体化的集合
113                     //如果是car他便可以是IBuyable，IMoveable或者IItem
114                     var buyable = item as IBuyable; 
115                     
116                     if (buyable != null)
117                     {
118                         Console.Write("- cost {0}", buyable.Price);
119                     }
120 
121                     var moveable = item as IMoveable;
122                     //使用as可以新做一个临时的var，待右边等式成立把convert好的type传到左边
123                     //如果as可行，it will type the object as you ask it to
124                     //如果as不avaliable则返回null
125                     //as解决了run time type of object的问题
126 
127                     //Ibuyable buyable = (IBuyable)item;
128                     //上面也可行但是如果item不是Ibuyable抛出异常
129 
130                     if (moveable != null)
131                     {
132                         Console.Write("- can move");
133                     }
134                     Console.WriteLine();
135                     index++;
136                 }
137 
138                 Console.Write("Choose items: ");
139                 var itemIndex = int.Parse(Console.ReadLine());
140                 if (itemIndex <= 0 || itemIndex > items.Count)
141                 {
142                     Console.WriteLine("You are dumb");
143                     continue;
144                 }
145                 return items[itemIndex-1];
146             }
147         }
148     }
149 }

实例2：

准备好Icommand和Istate接口

View Code

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Text;
 5 using System.Threading.Tasks;
 6 
 7 namespace ConsoleApplication1.Abstract
 8 {
 9     interface ICommand
10     {
11         void Execute();
12     }
13 }
14 
15 
16 using System;
17 using System.Collections.Generic;
18 using System.Linq;
19 using System.Text;
20 using System.Threading.Tasks;
21 
22 namespace ConsoleApplication1.Abstract
23 {
24     interface IState
25     {
26         void Render();
27         ICommand GetCommand();
28     }
29 }

先做Statemanager.cs,这个相当于engine,换state并且执行该state的command

View Code

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Text;
 5 using System.Threading.Tasks;
 6 using ConsoleApplication1.Abstract;
 7 
 8 namespace ConsoleApplication1
 9 {
10     class StateManager
11     {
12         private IState _state;  //store current active state
13 
14         public void SwitchState(IState state) //switch current state to a new state
15         {
16             _state = state;
17         }
18 
19         public void Run(IState initialState)    //Run 方法take first state that going to use
20         {
21             _state = initialState;
22 
23             while (true)    //infinite loop render current state
24             {
25                 _state.Render();
26                 var command = _state.GetCommand();  //ask current state's command
27                 command.Execute();  //excuted command
28             }
29         }
30     }
31 }

再做第一个MainMenuState

posted @ 2013-04-25 10:40 若愚Shawn 阅读(211) 评论(0) 编辑收藏举报

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Interface笔记

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