Presentation of the "Mikado Method" and the book by Daniel Brolund and Ola Ellnestam

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Mikado Method
Jörn Dinkla, April 2020
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2. The story of refactoring
Once upon a time there was a smell in a programm ...
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1. You think “this can be made better, i’ll refactor it” …
2. You refactor it, run the tests, but something else breaks
3. You try to fix it and so you look at other places in the code
4. You think “this place smells, too”
5. Goto 1

3. The story of refactoring
Once upon a time there was a smell in a programm ...
3
© 2020 ThoughtWorks
1. You think “this can be made better, i’ll refactor it” …
2. You refactor it, run the tests, but something else breaks
3. You try to fix it and so you look at other places in the code
4. You think “this place smells, too”
5. Goto 1
After many hours of work:
Code is not compiling
Tests are broken
Hours wasted

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© this image is taken from the book

5. What is wrong with this approach?
Why doesn’t it work?
How can this rabbit hole be avoided?
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6. Ola Ellnestam, Daniel Brolund
Manning, 2014
Important parts are available online:
https://www.manning.com/books/the-mikado-method
The Mikado Method
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7. “The Mikado Method is a structured way to make
significant changes to complex code/complex
systems.”
Ellnestam, Brolund
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The trick is to pick up
the easy sticks first

9. “The Mikado Method lets you handle complex code
a bit like you’d move furniture around in your
home, one piece at a time.”
Ellnestam, Brolund
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11. What are the easiest parts?
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Difficult to answer in
complex situations!

12. Goal
The goal is to build up knowledge
● What obstacles are there?
● What are the dependencies?
Build a plan of easy steps!
Finding out the dependencies of the sticks or furniture
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13. The Mikado Method
1. Set a goal.
2. An experiment is a procedure for making a discovery or
establishing the validity of a hypothesis, so that you can
see what parts of the system break.
3. Visualization happens when you write down the goal
and the prerequisites necessary to achieve it.
4. Undo your changes to restore a previously working state.
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14. Comparison
1. Set a goal
2. Experiment
3. Visualize
4. Undo
Finding out the dependencies of the sticks
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Traditionally
top-down
Mikado
Top-down
bottom-up

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16. Undo
Really?
● “the undo part is what people struggle with most”
● “undoing feels very unintuitive and wasteful”
But, it is important
● It’s learning, we need complete information
● We do not want to rely on assumptions
● You can save progress in patches
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17. Breaking up a complex problem in simple ones
Analyse top down
● Build the graph with partial solutions
● Undo to return to a correct system state
● Until something won’t break other parts
Rewind bottom-up
● Apply the small changes
● Do not require large feature branches
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18. Advantages
● Learned about the whole problem
● Solution consists of small changes
○ Can be worked in in small tickets/stories
○ Do not require large feature branches
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21. Most chapters are available online
https://www.manning.com/books/the-mikado-method
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Jörn Dinkla
jdinkla@thoughtworks.com
© 2020 ThoughtWorks