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Loving Legacy Code Keith Pitty

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Loving legacy code?

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Seriously?

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Do you love legacy code?

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Legacy deserves respect!

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More love!

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Approach Techniques Attitude

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What is legacy code?

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No tests? What is legacy code?

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Impedes change What is legacy code?

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Why so negative?

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Technical debt? Why so negative?

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Poor design Why so negative?

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Obfuscation Why so negative?

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Counterproductive tests Why so negative?

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No “shiny” tech? Why so negative?

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Tender loving care

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OK, maybe beyond TLC

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Or maybe not …

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Original developers?

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Understand why Original developers?

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Respect Original developers?

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Learn from mistakes Original developers?

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Approach Techniques Attitude

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Pain points

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Customer feedback Pain points

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Monitoring tools Pain points

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Listen to developers Pain points

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Measure code quality Pain points

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Nursing legacy code

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Version control! Nursing legacy code

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Testing

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No tests? Nursing legacy code: testing

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Unit tests Nursing legacy code: testing

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Fast feedback Nursing legacy code: testing

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Break dependencies Nursing legacy code: testing

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Nurture tests Nursing legacy code: testing

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Remove tests? Nursing legacy code: testing

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Nurture CI builds Nursing legacy code: testing

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Refactoring

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Refactor judiciously Nursing legacy code: refactoring

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Separate concerns Nursing legacy code: refactoring

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e.g. Rails models Nursing legacy code: refactoring

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Nursing legacy code

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Service classes Nursing legacy code: refactoring

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“Best” Practices Nursing legacy code: refactoring

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Simplify design Nursing legacy code: refactoring

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1. Tests pass 2. Expresses intent 3. No duplication 4. Small Nursing legacy code: refactoring

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“Remove duplication and improve names in small cycles.” — JB Rainsberger Nursing legacy code: refactoring

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Less code Nursing legacy code: refactoring

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Satisfaction Nursing legacy code: refactoring

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Design Opportunities Nursing legacy code: refactoring

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Tool support

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Nursing legacy code: tool support

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RuboCop Nursing legacy code: tool support

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Other open source Section

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Automate workflow Nursing legacy code: tool support

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Managing legacy code

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Invest wisely Managing legacy code

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Maintenance effort Managing legacy code

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Maintenance budget Managing legacy code

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If necessary … Managing legacy code

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migrate away Managing legacy code

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Approach Techniques Attitude

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Approach Techniques Attitude

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Managers

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Devote resources Managers

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Listen to developers Managers

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Respect Managers

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Share support roles Managers

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Developers

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Share knowledge Developers

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GitHub PRs Developers

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Future Developers

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Language Developers

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Respect past Developers

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No codebase is perfect Developers

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Listen to managers Developers

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Respect Developers

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Metaphors

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Nursing Metaphors

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Gardening Metaphors

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Renovation Metaphors

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Conclusion

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Loving legacy code …

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can be rewarding

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Respect

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Thanks for listening!

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Keith Pitty @keithpitty