步步为营 .NET 代码重构学习笔记 九
2011-05-30 23:14 by spring yang, 1108 visits, 网摘, 收藏, 编辑步步为营 .NET 代码重构学习笔记系列
步步为营 .NET 代码重构学习笔记 二、提炼方法(Extract Method)
步步为营 .NET 代码重构学习笔记 三、内联方法(Inline Method)
步步为营 .NET 代码重构学习笔记 四、临时变量(Temporary Variable)
步步为营 .NET 代码重构学习笔记 五、分解函数和替换算法(Replace Method And Substitute Algorithm)
步步为营 .NET 代码重构学习笔记 六、移动函数和移动值域(Move Method And Move Field)
一、Duplicate Observed Data（复制[被监视数据]）
动机（Motivation）
将该笔数据拷贝到一个domain object中。建立一个Observer模式，用以对domain object 和GUI object内的重复数据进行同步控制（sync）。
示例
步步为营 .NET 设计模式学习笔记 十二、Observer (观察者模式)
二、Change Unidirectional Association to Bidirectional（将单向关联改为双向）
动机（Motivation）
添加一个反指针，并使修改函数（modifiers）能够同时更新两条连接。
示例
01 |
public class Order |
02 |
{ |
03 |
private Customer _customer; |
04 |
05 |
public Customer NewCustomer |
06 |
{ |
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get { return _customer; } |
08 |
set { _customer = value; } |
09 |
} |
10 |
} |
11 |
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public class Customer |
13 |
{ |
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} |
改为
01 |
public class Order |
02 |
{ |
03 |
public List<Customer> CustomerList = new List<Customer>(); |
04 |
05 |
public void AddCustomer(Customer arg) |
06 |
{ |
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arg.orderlist.Add(this); |
08 |
CustomerList.Add(arg); |
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} |
10 |
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public void RemoveCustomer(Customer arg) |
12 |
{ |
13 |
arg.orderlist.Remove(this); |
14 |
CustomerList.Remove(arg); |
15 |
} |
16 |
} |
17 |
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public class Customer |
19 |
{ |
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public List<Order> orderlist = new List<Order>(); |
21 |
public void AddOrder(Order arg) |
22 |
{ |
23 |
arg.CustomerList.Add(this); |
24 |
orderlist.Add(arg); |
25 |
} |
26 |
public void RemoveOrder(Order arg) |
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{ |
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arg.CustomerList.Remove(this); |
29 |
orderlist.Remove(arg); |
30 |
} |
31 |
} |
三、Change Bidirectional Association to Unidirectional（将双向改为单向）
动机（Motivation）
两个classes之间有双向关联，但其中一个class如今不再需要另一个class的特性。
示例
01 |
public class Order |
02 |
{ |
03 |
public List<Customer> CustomerList = new List<Customer>(); |
04 |
05 |
public void AddCustomer(Customer arg) |
06 |
{ |
07 |
arg.orderlist.Add(this); |
08 |
CustomerList.Add(arg); |
09 |
} |
10 |
11 |
public void RemoveCustomer(Customer arg) |
12 |
{ |
13 |
arg.orderlist.Remove(this); |
14 |
CustomerList.Remove(arg); |
15 |
} |
16 |
} |
17 |
18 |
public class Customer |
19 |
{ |
20 |
public List<Order> orderlist = new List<Order>(); |
21 |
public void AddOrder(Order arg) |
22 |
{ |
23 |
arg.CustomerList.Add(this); |
24 |
orderlist.Add(arg); |
25 |
} |
26 |
public void RemoveOrder(Order arg) |
27 |
{ |
28 |
arg.CustomerList.Remove(this); |
29 |
orderlist.Remove(arg); |
30 |
} |
31 |
} |
改为
01 |
public class Order |
02 |
{ |
03 |
private Customer _customer; |
04 |
05 |
public Customer NewCustomer |
06 |
{ |
07 |
get { return _customer; } |
08 |
set { _customer = value; } |
09 |
} |
10 |
} |
11 |
12 |
public class Customer |
13 |
{ |
14 |
} |
四、Replace Magic Number with Symbolic Constant（以符号常量/字面常量取侙魔法数）
动机（Motivation）
创造一个常量，根据其意义为它命名，并将上述的字面数值替换为这个常量。
示例
1 |
public double PotentialEnergy(double mass, double height) |
2 |
{ |
3 |
return mass * 9.51 * height; |
4 |
} |
改为
1 |
private double GRAVITATIONAL_CONSTANT = 9.51; |
2 |
public double PotentialEnergy(double mass, double height) |
3 |
{ |
4 |
return mass * GRAVITATIONAL_CONSTANT * height; |
5 |
} |
五、Encapsulate Field（封装值域）
动机（Motivation）
将它声明为private，并提供相应的访问函数（accessors）
示例
1 |
public string _name; |
改为
1 |
private string _name; |
2 |
3 |
public string Name |
4 |
{ |
5 |
get { return _name; } |
6 |
set { _name = value; } |
7 |
} |
六、Replace Type Code with Class（以类取代型别码）
动机（Motivation）
以一个新的class替换该数值型别码（type code）
示例
01 |
public class Person |
02 |
{ |
03 |
public int O = 0; |
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public int A = 1; |
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public int B = 2; |
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public int AB = 3; |
07 |
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private int _bloodGroup; |
09 |
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public Person(int bloodGroup) |
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{ |
12 |
_bloodGroup = bloodGroup; |
13 |
} |
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public int NewBloodGroup |
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{ |
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get { return _bloodGroup; } |
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set { _bloodGroup = value; } |
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} |
19 |
} |
改为
01 |
public class Person |
02 |
{ |
03 |
public int O = BloodGroup.O.Code; |
04 |
public int A = BloodGroup.A.Code; |
05 |
public int B = BloodGroup.B.Code; |
06 |
public int AB = BloodGroup.AB.Code; |
07 |
08 |
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private int _bloodGroup; |
10 |
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public Person(int bloodGroup) |
12 |
{ |
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_bloodGroup = bloodGroup; |
14 |
} |
15 |
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public int NewBloodGroup |
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{ |
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get { return _bloodGroup; } |
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set { _bloodGroup = value; } |
20 |
} |
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} |
22 |
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public class BloodGroup |
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{ |
25 |
public static BloodGroup O = new BloodGroup(0); |
26 |
public static BloodGroup A = new BloodGroup(1); |
27 |
public static BloodGroup B = new BloodGroup(2); |
28 |
public static BloodGroup AB = new BloodGroup(3); |
29 |
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private int _code; |
31 |
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private BloodGroup(int code) |
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{ |
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_code = code; |
35 |
} |
36 |
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public int Code |
38 |
{ |
39 |
get { return _code; } |
40 |
set { _code = value; } |
41 |
} |
42 |
43 |
} |
