The presentation from DecompileD 2021

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
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
OBJECTIVE-C

5. @VladimirWrites

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

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REFACTOR REWRITE

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WE ARE THE SAME! OBJECTIVE-C

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6 months
Feature-freeze
Swift
Plan

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6 months
Feature-freeze
Swift
Plan
16 months
New features in
the old app
Features cut out
Objective-C
added

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60+ modules
Refactoring …
100% Kotlin
Trunk based
development

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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

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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

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What should YOU do?

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NO
Is the codebase really that bad?
YES
REFACTOR

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YES
Will there be new features?
NO
REFACTOR

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YES
Do you need more than 6 months?
NO
REFACTOR

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Can I rewrite the app now?
YES, BUT

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THANK
YOU!

26. @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

27. @VladimirWrites
Vladimir Jovanovic
vladimirj.dev
@VladimirWrites www.slideshare.net/VladimirWrites
QUESTIONS?