A quick-and-dirty introduction to Design Smells, as presented in Robert 'Uncle Bob' Martin book "Agile Software Development". Thought as the first of a series.

1. D esign S mells The 7 Odors of R otting S oftware G iorgio V espucci – S oftware F actory R oma

2. ?

3. W hat is

4. S oftware D esign

5. ?

6. “ […] the design of a software project is documented primarily by its source code .” Robert C. Martin

7. The source code is the design.

8. Abandoned code rots .

9. When it rots, it smells .

10. 7 S mells

11. 1. R igidity

12. The tendency for software to be difficult to change , even in simple ways. The design is hard to change .

13. 2. F ragility

14. The tendency of a program to break in many places when a single change is made. The design is easy to break .

15. 3. I mmobility

16. It is hard to disentangle the system into components that can be reused in other systems. The design is hard to reuse .

17. 4. V iscosity

18. S oftware viscosity

19. Design -preserving methods vs. Hacks

20. E nvironment viscosity

21. Slow and inefficient development environment Very long compile times Hours to check-in Several minutes to deploy

22. Doing things wrong is easier than doing things right .

23. 5. N eedless C omplexity

24. Elements not currently useful in the design. O verdesign.

25. 6. N eedless R epetition

26. C ut- a nd- p aste is useful for text-editing, but can be disastrous for c ode- e diting.

27. The design contains repeating structures that could be unified under a single abstraction.

28. 7. O pacity

29. The tendency of a module to be difficult to understand .

30. Code written in a clear and expressive manner vs. Code written in an opaque and convoluted manner.

31. ?

32. W hat is a

33. D esign S mell

34. ?

35. A d esign s mell is a symptom .

36. It’s a violation of P rinciples.

37. S . O . L . I . D . Principles

38. T o be c ontinued...