Refactoring Day 3 : Pull Up Method

The Pull Up Method refactoring is the process of taking a method and “Pulling” it up in the inheritance 
chain. This is used when a method needs to be used by multiple implementers. 
 1: public abstract class Vehicle 
 2: { 
 3: // other methods 
 4: } 
 5: 
 6: public class Car : Vehicle 
 7: { 
 8: public void Turn(Direction direction) 
 9: { 
 10: // code here 
 11: } 
 12: } 
 13: 
 14: public class Motorcycle : Vehicle 
 15: { 
 16: } 
 17: 
 18: public enum Direction 
 19: { 
 20: Left, 
 21: Right 
 22: } 
 
As you can see, our Turn method is currently only available to the car class, we also want to use it in the 
motorcycle class so we create a base class if one doesn’t already exist and “pull up” the method into the 
base class making it available to both. The only drawback is we have increased surface area of the base 
class adding to it’s complexity so use wisely. Only place methods that need to be used by more that one 
derived class. Once you start overusing inheritance it breaks down pretty quickly and you should start to 
lean towards composition over inheritance. Here is the code after the refactoring: 
 1: public abstract class Vehicle 
 2: { 
 3: public void Turn(Direction direction) 
 4: { 
 5: // code here 
 6: } 
 7: } 
 8: 
 9: public class Car : Vehicle 
 10: { 
 11: } 
 12: 
 13: public class Motorcycle : Vehicle 
 14: { 
 15: } 
 16: 
 17: public enum Direction 
 18: { 
 19: Left, 
 20: Right 
 21: }