31天重构指南之二：移动方法

今天的重构指南是关于移动方法的，移动方法是一个简单却容易被忽略的重构，正如它的名字所表达的意思一样，移动方法就是将方法移动到合适的位置。让我们来看下面的待重构代码：

   1: public class BankAccount

   2: {

   3:     public BankAccount(int accountAge, int creditScore, AccountInterest accountInterest)

   4:     {

   5:         AccountAge = accountAge;

   6:         CreditScore = creditScore;

   7:         AccountInterest = accountInterest;

   8:     }

   9:  

  10:     public int AccountAge { get; private set; }

  11:     public int CreditScore { get; private set; }

  12:     public AccountInterest AccountInterest { get; private set; }

  13:  

  14:     public double CalculateInterestRate()

  15:     {

  16:         if (CreditScore > 800)

  17:             return 0.02;

  18:  

  19:         if (AccountAge > 10)

  20:             return 0.03;

  21:  

  22:         return 0.05;

  23:     }

  24: }

  25:  

  26: public class AccountInterest

  27: {

  28:     public BankAccount Account { get; private set; }

  29:  

  30:     public AccountInterest(BankAccount account)

  31:     {

  32:         Account = account;

  33:     }

  34:  

  35:     public double InterestRate

  36:     {

  37:         get { return Account.CalculateInterestRate(); }

  38:     }

  39:  

  40:     public bool IntroductoryRate

  41:     {

  42:         get { return Account.CalculateInterestRate() < 0.05; }

  43:     }

  44: }

上面代码中让我们感兴趣的是BankAccount.CalculateInterest方法，我们需要对它进行重构，重构的提示是我们需要将方法定义在对它使用最多的类中。在这个例子中，我们要将

BankAccount.CalculateInterest方法移动到AccountInterest类中。重构后的代码如下：

   1: public class BankAccount

   2: {

   3:     public BankAccount(int accountAge, int creditScore, AccountInterest accountInterest)

   4:     {

   5:         AccountAge = accountAge;

   6:         CreditScore = creditScore;

   7:         AccountInterest = accountInterest;

   8:     }

   9:  

  10:     public int AccountAge { get; private set; }

  11:     public int CreditScore { get; private set; }

  12:     public AccountInterest AccountInterest { get; private set; }

  13: }

  14:  

  15: public class AccountInterest

  16: {

  17:     public BankAccount Account { get; private set; }

  18:  

  19:     public AccountInterest(BankAccount account)

  20:     {

  21:         Account = account;

  22:     }

  23:  

  24:     public double InterestRate

  25:     {

  26:         get { return CalculateInterestRate(); }

  27:     }

  28:  

  29:     public bool IntroductoryRate

  30:     {

  31:         get { return CalculateInterestRate() < 0.05; }

  32:     }

  33:  

  34:     public double CalculateInterestRate()

  35:     {

  36:         if (Account.CreditScore > 800)

  37:             return 0.02;

  38:  

  39:         if (Account.AccountAge > 10)

  40:             return 0.03;

  41:  

  42:         return 0.05;

  43:     }

  44: }

原文链接：http://www.lostechies.com/blogs/sean_chambers/archive/2009/08/02/refactoring-day-2-move-method.aspx