The scary fairy tale about MVC or How to stop worrying and start to write ruby code

Hotcode conference, 5 May 2013

Transcript

1. The scary fairy tale about MVC How to stop worrying and start to write ruby code or
2. Andrey Savchenko @ptico @ptico_eng Aejis
3. Cast • Little Red Riding Hood - developer • Grandmother - customers • The map - MVC • Compass - Rails And others…
4. nce upon a time, a little girl goes trough the scary wood to deliver pies to her grandmother. O
5. here she met the Damn Horrible Human nicknamed «The Wolf» T
6. here you are going, little girl? he asked. I’m going to deliver pies to my grandma – she answered. W –
7. have a present for you – wolf said. Take this map and this compass: it works very well for me. I
9. he girl took gifts and moved on. And have lost in the wood. Because the compass was point to the wolf’s grandmother and map defines the ways not applicable for little girls. T
10. THE END
11. Moral: the tools which works for other person may doesn’t work for you
12. MVC is a good example
13. What’s wrong with MVC?
14. It has only three letters MVC
15. One of them superfluous MVC
16. Application should know nothing about representation
17. Another one means a little bit more than nothing MVC
18. The controller should delegate the work that needs to be done to other objects; it coordinates or controls the activity. It should not do much work itself. GRASP controller definition
19. So, what’s left?
20. The model M
21. M
22. M
23. M
25. Please, rise your hand if you have this kind of models
26. So, this is a moment when we should start writing the Ruby code
27. What does it mean?
28. Lets take a look at our daily gems
29. carrierwave
30. state_machine
31. resque
32. Ok, i catch the idea, lets start!
33. Wait a minute - we need some weapons
34. Metrics
35. Metrics • WPM - WTFs per minute
36. Metrics • WPM - WTFs per minute • SLOC/M - Source lines of code per method
37. Metrics • WPM - WTFs per minute • SLOC/M - Source lines of code per method • SLOC/C - Source lines of code per class
38. Overall complexity ((AVG(SLOC/M) + SLOC/C)^WPM)/100
39. Overall complexity If you have > 10 – i have a bad news for you
40. Principles • SOLID
41. Principles • SOLID • YAGNI
42. Principles • SOLID • YAGNI • KISS
43. Secret weapon: Testability
44. The simpler your objects to test - the easier they can be changed and reused
45. The more complex your objects is - the harder to test them
46. Got it! What about strategy?
47. Strategies:
48. Use-case strategy
49. Use-case strategy • Doesn’t work with Rails • Requires to build your own stack • But once you build this – its bullet-proof
50. Onion strategy
52. Onion strategy • Do work with Rails • Layer can be just Plain Old Ruby Object • Layers is hard to naming
53. Onion strategy Model Controller View
54. Onion strategy Model Controller View Presenter
55. Onion strategy Model Controller View Presenter Form object
56. Onion strategy Model Controller View Presenter Form object Repository
57. Onion strategy Model Controller View Presenter Form object Repository Service
58. Onion strategy Model Controller View Presenter Form object Repository Service Validator
59. Attribution: http://www.flickr.com/photos/42255449@N00/7177978063/ http://www.flickr.com/photos/normanbleventhalmapcenter/2674605704/ Thank you!
60. Questions? Andrey Savchenko Aejis* * we are hiring** ** if you understand the problem described in talk