We all "know" how to setup a new project architecture. The real challenge is in fixing the existing one. The presentation is going to show us how to clean and organize our existing project's code into patterns with a sequence of low-level refactorings. We are going to learn to: - Identify the best candidates for refactor; - Improve the design of the existing code - with solution to recurring design problems; - To refactor or not to refactor to a pattern - Become a better software engineers by making important changes safely and effectively;

3. Why your code sucks and how
to fix it
Marjan Nikolovski
Senior Software Engineer, Seavus
Co-Owner, EmitKnowledge
emitknowledge.com/@mnikolovski
mk.linkedin.com/in/marjannikolovski

4. Agenda
Refactoring: Why, When
Why your code sucks
How to fix it
Refactoring cheat list

5. Refactoring
A change made to the internal structure of
software to make it easier to understand and
cheaper to modify without changing its
observable behavior

6. Why refactoring – Technical factors
Make your code easier to understand
Make it easier to add new code
Improve the design of the codebase
Remove unused code
Better understanding of your codebase
Evolve your architecture instead of over
engineering it

7. Why refactoring – Psychological factors
Learn to embrace the change
Refactors are result of code reviews. Accept
that sometimes your code sucks !
Loose your fear to change existing codebase

8. When to refactor
Add new functionality
– Refactor existing code to make the change with
ease
Find bugs
– Refactor to understand the code
Code reviews
– Immediate results of the code review
End of a development iteration
– Fix what is shitty

9. Why your code sucks
 Your code sucks if it doesn't work
 Your code sucks if it isn't testable
 Your code sucks if it's hard to read
 Your code sucks if it's not understandable
 Your code sucks if overuse a trendy framework at the cost of following good
design/implementation practices
 Your code sucks if it has duplication
 Your code sucks if your function names suck
 Your code sucks if your variable names suck
 Your code sucks if your class names suck
 Your code sucks if your abstractions suck
 Your code sucks if a method is larger than the screen
 Your code sucks if you are reusing variables
 Your code sucks if you need to use comments to explain the code
 Your code sucks if an exception's stack trace doesn't return the original problem

10. Your code sucks if it doesn't work

11. Your code sucks if it isn't testable

12. Your code sucks if it's hard to read

13. Your code sucks if it's not
understandable

14. Your code sucks if overuse a trendy
framework at the cost of following
good design/implementation practices

15. Your code sucks if it has duplication

16. Your code sucks if your function names
suck

17. Your code sucks if your variable names
suck

18. Your code sucks if your class names
suck

19. Your code sucks if your abstractions
suck

20. Your code sucks if a method is larger
than the screen

21. Your code sucks if you are reusing
variables

22. Your code sucks if you need to use
comments to explain the code

23. Your code sucks if an exception's stack
trace doesn't return the original
problem

24. How to fix it
Duplicated code
Long method
Primitive obsession
Switch statements
Long Parameter List

25. Duplicate code
Create a new common method
Use inheritance
Use template methods

26. Create a new common method

27. Use inheritance

28. Use template methods

29. Long method
Use extract to method
Minimize code nesting to maximum 1 level
with method extraction
Extract each iteration as a method
Extract multiple conditions as method

30. Long method

31. Primitive obsession
Overuse of primitive types in classes instead
of creating domain entities
Replace primitives with classes

32. Primitive obsession

33. Switch statements
Use command pattern to replace switch logic

34. Long Parameter List
Replace long param list with a class

35. Refactoring cheat list
 Replace Conditional with Polymorphism
 Remove Double Negative
 Replace Nested Conditional with Guard Clauses
 Reverse Conditional
 Replace Magic Number with Symbolic Constant
 Replace Exception with Test
 Encapsulate Downcast
 Consolidate Duplicate Conditional Fragments
 Consolidate Conditional Expression

36. Replace Conditional with
Polymorphism

37. Remove Double Negative

38. Reverse Conditional

39. Replace Nested Conditional with
Guard Clauses

40. Replace Magic Number with Symbolic
Constant

41. Replace Exception with Test

42. Encapsulate Downcast

43. Consolidate Duplicate Conditional
Fragments

44. Consolidate Conditional Expression

45. Questions?
• Complete electronic evaluation
forms on the computers in the
hall and enter to win!
– Telerik Ultimate Collection
– CodeSmith Tools Generator Pro
Personal
– JetBrains ReSharper
– Seavus EDC training vouchers
– Pluralsight subscriptions
– and many more…