Refactoring Day 2 : Move Method

The refactoring today is pretty straightforward, although often overlooked and ignored as being a 
worthwhile refactoring. Move method does exactly what it sounds like, move a method to a better 
location. Let’s look at the following code before our refactoring: 
 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: } 
 
The point of interest here is the BankAccount.CalculateInterest method. A hint that you need the Move 
Method refactoring is when another class is using a method more often then the class in which it lives. If 
this is the case it makes sense to move the method to the class where it is primarily used. This doesn’t work 
in every instance because of dependencies, but it is overlooked often as a worthwhile change. 
In the end you would end up with something like this: 
 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: } 
 
Simple enough! 

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