步步为营 .NET 代码重构学习笔记系列

 

 

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

 

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

public class Order    {        private Customer _customer;        public Customer NewCustomer        {            get { return _customer; }            set { _customer = value; }        }    }    public class Customer    {    }

 

改为

public class Order    {        public List
    
      CustomerList = new List
     
      ();        public void AddCustomer(Customer arg)        {            arg.orderlist.Add(this);            CustomerList.Add(arg);        }        public void RemoveCustomer(Customer arg)        {            arg.orderlist.Remove(this);            CustomerList.Remove(arg);        }    }    public class Customer    {        public List
      
        orderlist = new List
       
        ();        public void AddOrder(Order arg)        {            arg.CustomerList.Add(this);            orderlist.Add(arg);        }        public void RemoveOrder(Order arg)        {            arg.CustomerList.Remove(this);            orderlist.Remove(arg);        }    }
       
      
     
    

 

 

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

public class Order    {        public List
    
      CustomerList = new List
     
      ();        public void AddCustomer(Customer arg)        {            arg.orderlist.Add(this);            CustomerList.Add(arg);        }        public void RemoveCustomer(Customer arg)        {            arg.orderlist.Remove(this);            CustomerList.Remove(arg);        }    }    public class Customer    {        public List
      
        orderlist = new List
       
        ();        public void AddOrder(Order arg)        {            arg.CustomerList.Add(this);            orderlist.Add(arg);        }        public void RemoveOrder(Order arg)        {            arg.CustomerList.Remove(this);            orderlist.Remove(arg);        }    }
       
      
     
    

 

 

改为

public class Order    {        private Customer _customer;        public Customer NewCustomer        {            get { return _customer; }            set { _customer = value; }        }    }    public class Customer    {    }

 

 

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

public double PotentialEnergy(double mass, double height)        {            return mass * 9.51 * height;        }

 

 

改为

private double GRAVITATIONAL_CONSTANT = 9.51;        public double PotentialEnergy(double mass, double height)        {            return mass * GRAVITATIONAL_CONSTANT * height;        }

 

 

 

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

public string _name;

 

 

改为

private  string _name;        public string Name        {            get { return _name; }            set { _name = value; }        }

 

 

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

public class Person    {        public  int O = 0;        public  int A = 1;        public  int B = 2;        public  int AB = 3;        private int _bloodGroup;        public Person(int bloodGroup)        {            _bloodGroup = bloodGroup;        }        public int NewBloodGroup        {            get { return _bloodGroup; }            set { _bloodGroup = value; }        }    }

 

改为

public class Person    {        public int O = BloodGroup.O.Code;        public int A = BloodGroup.A.Code;        public int B = BloodGroup.B.Code;        public int AB = BloodGroup.AB.Code;        private int _bloodGroup;        public Person(int bloodGroup)        {            _bloodGroup = bloodGroup;        }        public int NewBloodGroup        {            get { return _bloodGroup; }            set { _bloodGroup = value; }        }    }    public class BloodGroup    {        public static BloodGroup O = new BloodGroup(0);        public static BloodGroup A = new BloodGroup(1);        public static BloodGroup B = new BloodGroup(2);        public static BloodGroup AB = new BloodGroup(3);        private int _code;        private BloodGroup(int code)        {            _code = code;        }        public int Code        {            get { return _code; }            set { _code = value; }        }    }