The presentation from MobOS 2020 in Cluj-Napoca, Romania.

1. FlixMobility
Rewrite or Refactor That Is the Question
Vladimir Jovanović
vladimirj.dev
@VladimirWrites

2. @VladimirWrites

3. @VladimirWrites
PAINFUL TO WORK ON
SLOW
ONBOARDING
BUGS
SLOW DEVELOPMENT
TODOs

4. @VladimirWrites
PAINFUL TO WORK ON
SLOW
ONBOARDING
BUGS
SLOW DEVELOPMENT
TODOs
PAINFUL TO WORK ON
SLOW
ONBOARDING
BUGS
SLOW DEVELOPMENT
TODOs

5. @VladimirWrites
PAINFUL TO WORK ON
SLOW
ONBOARDING
BUGS
SLOW DEVELOPMENT
TODOs
PAINFUL TO WORK ON
SLOW
ONBOARDING
BUGS
SLOW DEVELOPMENT
TODOs
OBJECTIVE-C

6. @VladimirWrites
• Founded in 2013 in Germany
• It expanded rapidly in the EU
market
• 2018 – started operating in the
US
• Provides:
• network planning
• marketing
• pricing
• quality management
• and customer service to our
partner companies

7. @VladimirWrites

8. @VladimirWrites

9. @VladimirWrites
All startup companies spend their first
years creating legacy code.
And there is nothing wrong with it.

10. @VladimirWrites

11. @VladimirWrites

12. @VladimirWrites

13. @VladimirWrites

14. @VladimirWrites
REFACTOR REWRITE

15. @VladimirWrites
WE ARE THE SAME!

16. @VladimirWrites
WE ARE THE SAME! OBJECTIVE-C

17. @VladimirWrites
6 months
Feature-freeze
Swift
Plan
10 months
New features in
the old app
Features cut out
Objective-Cadded

18. @VladimirWrites
45+ modules
55% Kotlin
Trunk based
developmentRefactoring …

19. @VladimirWrites
Cons:
A lot of planning
No new features
No direct benefit to the
customers
Some features are lost
It takes longer than
expected
Huge risk
Pros:
Greenfield project
New technologies
Clean codebase
Pros:
Greenfield project
New technologies
Clean codebase
Rewrite

20. @VladimirWrites
Cons:
Painfully slow
Requires careful planning
Hard for developers
Refactoring
Pros:
Constant value
Not losing knowledge
Lower risk
Continuous user testing

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The total cost of refactoring is always
higher than doing a complete rewrite
but the impact on the organisation
is usually much smaller

22. @VladimirWrites
What should YOU do?

23. @VladimirWrites
It’s harder to read code than to write it
but it’s a bit easier to read it if you had written it.

24. @VladimirWrites

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I don’t like
the code style
It uses Framework
and not Framework
Java Sux!
I don’t understand
the codebase

26. @VladimirWrites

27. @VladimirWrites
Is the codebase really that bad?

28. @VladimirWrites
NO
Is the codebase really that bad?
YES
REFACTOR

29. @VladimirWrites
Will there be new features?

30. @VladimirWrites
YES
Will there be new features?
NO
REFACTOR

31. @VladimirWrites
Do you need more than 6 months?

32. @VladimirWrites
YES
Do you need more than 6 months?
NO
REFACTOR

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35. @VladimirWrites
Can I rewrite the app now?

36. @VladimirWrites
Can I rewrite the app now?
YES

37. @VladimirWrites
Can I rewrite the app now?
YES, BUT

38. 15FlixMobility
THANK
YOU!

39. @VladimirWrites
Credits:
Articles:
• https://www.skcript.com/svr/rewrite-your-app-from-scratch/
• https://dev.to/rhymes/a-big-rewrite-5gl5
• https://daedtech.com/rewrite-or-refactor/
• https://gggritso.com/legacy-code
• https://ovid.github.io/articles/a-simple-way-to-fix-legacy-code.html
• https://www.joelonsoftware.com/2000/04/06/things-you-should-never-do-part-i/
Images:
• https://www.publicdomainpictures.net/en/view-image.php?
image=67199&picture=cooked-fresh-spaghetti
• https://emojipedia.org

40. @VladimirWrites15FlixMobility
Vladimir Jovanović
vladimirj.dev
@VladimirWrites www.slideshare.net/VladimirWrites www.flix.careers
QUESTIONS?