Elegant Objects and Cactoos

Overview of the EO paradigm and small overview of the Cactoos library for Porto Codes Meetup

Transcript

1. Elegant objects & Cactoos Filipe Freire
 21 December 2017
2. Quick intro Learner, tester, developer, husband
 OSS contributor 2y work as a “coding” tester
 1y work as a developer Currently @ filfreire.com 2
3. Elegant Objects 3
4. It’s an OOP paradigm 4
5. Book Yegor Bugayenko @yegor256 www.yegor256.com 5
6. Book Yegor Bugayenko @yegor256 www.yegor256.com Set of recommendations: - Cleaner code - Better classes - Visible architecture 6
7. Disclaimer: You can find out more at yegor256.com Youtube @yegor256 and on the EO books. 7
8. So, what are the recommendations? 8
9. Getters Setters Mutable objects Static methods Annotations Data Objects Type Casting Etc. 9
10. Getters Setters Mutable objects Static methods Annotations Data Objects Type Casting Etc. 10
11. Don’t treat objects as 
 data structures bags of data.
 Ever. 11
12. Maintainability > everything else 12
13. “Objects as living beings” Birth Working life Retirement 13
14. Some examples… 14
15. Birth 15
16. Code Free Constructors 16
17. 17
18. “Object’s name != job title” 18
19. Object’s name != job title Meaning: Avoid the use of “-ER” 19
20. Helper, Handler, Writer, Reader,
 Converter, Observer, Listener, Sorter, Encoder, Decoder, … 20
21. Helper, Handler, Writer, Reader,
 Converter, Observer, Listener, Sorter, Encoder, Decoder, … 21
22. An object isn’t: 1) A link between worlds 2) A collection of procedures 
 plus data 22
23. An object is: 1) Self-sufficient 2) Representative of 
 encapsulated data 23
24. A Finder of Prime Numbers vs A List of numbers that 
 returns only primes 24
25. Education & Work life 25
26. No Getters and Setters.
 Not even once. 26
27. No Getters and Setters
 ?! ?! 27
28. Again, don’t treat objects as 
 bags of data.
 Ever. 28
29. Computer-style: 29
30. Human-style: 30
31. “An object works by contracts” 31
32. “An object works by contracts” Always use interfaces 32
33. Example “I want results for a Tennis match” Tennis_31Feb.xlsx TENNIS.txt tennis_res.json Sources: … 33
34. Example “I want results for a Tennis match” Tennis_31Feb.xlsx TENNIS.txt tennis_res.json Sources: … ExcelTennisMatch TextTennisMatch JsonTennisMatch 34
35. Example “I want results for a Tennis match” ExcelTennisMatch TextTennisMatch JsonTennisMatch TennisMatch GameMatch implement extends 35
36. Excel, Text, Json, etc. Contract stays the same More Decoupling and more Maintainability 36
37. “A good object should never change his encapsulated state.” 37
38. “A good object should never change his encapsulated state.” 38 Be immutable
39. This can change State is the same 39
40. Some benefits Thread Safety Avoiding Temporal Coupling Avoiding side effects Avoiding identity mutability (more at http://yegor256.com/2014/06/09/objects-should-be-immutable.html) 40
41. Retirement 41
42. Don’t accept null arguments Don’t return null 42
43. - Hello, is it a software department?
 - Yes.
 - Let me talk to your employee "Jeffrey" please.
 - Hold the line please...
 - Hello.
 - … 43
44. - Hello, is it a software department?
 - Yes.
 - Let me talk to your employee "Jeffrey" please.
 - Hold the line please...
 - Hello.
 - Are you NULL? (more at http://www.yegor256.com/2014/05/13/why-null-is-bad.html) 44
45. There’s more to it, Let’s save it for another talk 45
46. https://github.com/yegor256/cactoos 46
47. Useful building blocks from Guava, Apache Commons, JDK
 + EO paradigm 47
48. Meaning… No null No code in constructors No getters and setters No mutable objects No static methods, not even private ones (among other stuff) 48
49. Example 1 49
50. Example 2 50
51. Example 3 51
52. Summing up 52
53. Maintainability 53
54. –W. Edwards Deming "Build quality into the product rather than trying to test it in later." 54
55. Quality from the start Force strict control of code quality. Ex: Static Analysis -> mandatory 55
56. Thank you. Questions? filfreire filrfreire filfreire.com 56