Principle to avoid speculative planning & programming. Thinking, knowing, feeling the business pulse.

1. YAGNI
Principle to avoid speculative
planning & programming

2. About me
• Gjero Krsteski
• Software Developer
• QuestBack GmbH, Germany
• Contributor: ZF1, Zurmo, phlexible
• father + trainer + musician
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3. What are your expectations?
• Reasons to practise it
• How and when to use YAGNI
• How does it work in reality
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4. Abbreviation for…
• You Ain’t Gonna Need It
• Keep it simple, stupid! = KISS
• Always implement things when
you actually need them, never when you
just foresee that you need them.
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5. The Ideas Behind YAGNI
Granularity Balance YAGNI
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6. Granularity
Don’t use bazooka
to clobber a fly!
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7. Balance
• can anticipate which way the project is likely
to go in the near future?
• might make sense to build particular things
now to cater for this?
• may have capacity now but will not
necessarily have it later?
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8. Reasons to practise it
• You save time
• Your code is more testable and maintainable
• Your code is cleaner and more robust
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9. Keep this principle in mind
No!
• Implement a pattern? Why?
• Use a utility library? What for!?
• Let us build more automation around our
deployment process?
Bah!!!
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10. What should I do?
• think first before you move (Bruce Lee)
• What's the cost of the investment?
• What is your time horizon?
• Opportunity cost?
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11. Ignorance is bliss
Who is
Who stupid?
do
that?
Who
Who
designed
manages
that box?
the
space?
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12. Secret twenty percent
20% of the effort is the
20% 80% of the results!
=> do the „right“ 20%
80%
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13. literature
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14. Gjero Krsteski The YAGNI principle 14

15. THANK YOU FOR YOUR ATTENTION
Have fun finding the “right” 20%
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