Legacy code & fun

Welcome all my name is Marco, I'm italian.
I've been writing in PHP pretty much since I was 20 and I worked as PHP developer in Italy, UK and here in Melbourne of course.

I don't know why exactly but a little bit everywhere I found myself to work on legacy code.

This presentation is going to be all about my experience, thoughts and ideas on legacy code.

I hope you'll enjoy :)

Transcript

1. 1 Legacy code & fun Thoughts and ideas about legacy code
2. Marco @borracciaBlu_u borracciaBlu borracciaBlu 2
3. What’s legacy code anyway? 3
5. • code written by other people • executable (in some way is working) • nobody is able to read the code (no tests) Legacy code properties: 5
6. • code written by other people • executable (in some way is working) • nobody is able to read the code (no tests) Legacy code properties: 6
7. http://blog.noctua-software.com/deal-with-legacy-code.html In one case I was specifically hired to replace the original maintainer who -as I later learned- left the company from a burnout caused by the frustration of having to maintain his own code. 7
8. Why the past developers quit ? 8
9. THE CODE WAS VERBOSE 9
10. THE CODE WAS COMPLEX 10
11. E.W.Dijkstra /dɛɪkstra/ My point today is that, if we wish to count lines of code, we should not regard them as “lines produced” but as “lines spent”: the current conventional wisdom is so foolish as to book that count on the wrong side of the ledger. 11
12. Succinctness is power. Paul Graham 12
13. So how could you survive ? 13
15. KNOW YOUR ENEMY Rule the code - Communicate the complexity 15
16. THE (ANTI)PATTERN NO SINGLE RESPONSIBILITY FLATTENING ARROW CODE VERBOSITY / COMPLEXITY 16
17. FLATTENING ARROW CODE 17
18. 18 FLATTENING ARROW CODE LOOKS LIKE
19. SINGLE RESPONSIBILITY FLATTENING ARROW CODE 19
20. POSSIBLE SOLUTIONS 20
21. IS/HAS/CAN FUNCTIONS (VARIABLES) 21
22. GUARD CLAUSES 22
23. CONSTANTS 23
24. • no documentation • no ownership • scared to change • bad deadlines Why it’s happening : 24
25. The boss ... 25
27. COMMUNICATE THE COMPLEXITY Communicate it does matter! 27
29. http://phpmd.org/rules/index.html 29
30. 1-4 is low complexity 5-7 is moderate complexity 8-10 is high complexity 11+ is very high complexity CYCLOMATIC COMPLEXITY 30
31. REDUCE THE JARGON 31
32. Last but not least 32
34. CODESTYLE 34
35. BE CLEAN AND CONSISTENT 35
36. BOY SCOUT RULE Leave your code better than you found it. 36
37. Life isn't black and white. It's a million gray areas, don't you find? BE INCREMENTAL 37
38. DON’T THROW YOUR OLD CODE FIX IT! 38
39. STUDY THE HISTORY (git, svn) 39
40. Questions? 40