Legacy code can be refactored if tests are written, even if the code is awful. Without tests, wonderful code is also difficult to change. There are four main reasons for changing software: adding features, fixing bugs, refactoring, and optimizing. The challenges in changing code are determining what to change, confirming the change is correct, and ensuring nothing else is broken. Not changing legacy code over time increases these risks and makes the code more complex and harder to work with.

1. Working effectively with legacy code 2010.12.23 geek—cafe, koduki - chapter 1 -

2. What is legacy code ?

3. not object oriented ?

4. NO

5. not beautiful ?

6. NO

7. nothing test ?

8. YES

9. If tests are written, an awful code is refactable. However, even a wonderful code is difficult change if there is no test.

10. 1. Changing Software.

12. Fixing a bug

13. Refactoring

14. Optimizing

15. Change reason and type Adding a feature Fixing a bug Refactoring Optimizing Structure change change change New Function change Function change Resource change Test Code change Change

17. How can I confirm the change is correct ?

18. How can I confirm anything is not broken ?

19. These are very difficult. So we fear the change.

21. skill down for changing software.

22. fear of changing grows more and more .

23. To Be Continued Chapter 2.