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Mikadomethod tad2011
- 1. Reclaim your legacy systems Toe-dipping and deep-diving with The Mikado Method Daniel Brolund @danielbrolund Ola Ellnestam @ellnestam #mikadomethod @mikadomethod http://mikadomethod.wordpress.com/book Thursday, March 17, 2011
- 2. 2-by-2 sharing: Code-change horror stories Thursday, March 17, 2011
- 3. Once upon a time, we were to change a codebase... Thursday, March 17, 2011
- 4. Thursday, March 17, 2011
- 5. Lets say this was our system... Thursday, March 17, 2011
- 6. A change We were to make a change... Thursday, March 17, 2011
- 7. ✘ ✘ ✘✘ A change ✘✘✘ ✘ ...but we got some errors... Thursday, March 17, 2011
- 8. ✘ ✘ ✘✘ A change ✘✘✘ ✘ Patching led to more errors... Thursday, March 17, 2011
- 9. ✘ ✘ ✘✘ ✘ ✘ ✘ ✘ ✘ ✘✘ A change ✘✘✘ ✘ Patching led to more errors... Thursday, March 17, 2011
- 10. ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘✘ ✘ ✘ ✘ ✘ ✘ ✘✘ A change ✘✘✘ ✘ Patching led to more errors... Thursday, March 17, 2011
- 11. ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘✘ ✘ ✘ ✘ ✘ ✘ ✘✘ A change ✘✘✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘✘ ✘ Patching led to more errors... Thursday, March 17, 2011
- 12. ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘✘ ✘ ✘ ✘ ✘ ✘ ✘✘ A change ✘✘✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘✘ ✘ ...and each patch led to even more errors... Thursday, March 17, 2011
- 13. ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘✘ ✘ ✘ ✘ ✘ ✘ A change ✘✘✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ...and each patch led to even more errors... Thursday, March 17, 2011
- 14. ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘✘ ✘ ✘ ✘ ✘ ✘ A change ✘✘✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ Like trying to stop the shockwave with our hands... Thursday, March 17, 2011
- 15. ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘✘ ✘ ✘ ✘ ✘ ✘ A change ✘✘✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘✘ ✘ ✘ ✘ ✘ ✘ ✘ ✘ We could only revert. Thursday, March 17, 2011
- 16. We could only revert. Thursday, March 17, 2011
- 17. Thursday, March 17, 2011
- 18. But we really needed to do that change! Thursday, March 17, 2011
- 19. A change The same change... Thursday, March 17, 2011
- 20. ✘✘ ✘ ✘ A change ✘✘✘ ✘ ...the same errors... Thursday, March 17, 2011
- 21. This time, we noted a prerequisite for each of the errors... ✘✘ ✘ ✘ A change ✘✘✘ ✘ Thursday, March 17, 2011
- 22. This time, we noted a prerequisite for each of the errors... Prereq ✘ ✘✘ ✘ A change ✘✘✘ ✘ Thursday, March 17, 2011
- 23. This time, we noted a prerequisite for each of the errors... Prereq ✘ Prereq ✘✘ ✘ A change ✘✘✘ ✘ Thursday, March 17, 2011
- 24. This time, we noted a prerequisite for each of the errors... Prereq ✘ Prereq ✘✘ ✘ A change ✘✘✘ Prereq ✘ Thursday, March 17, 2011
- 25. ...then we reverted the errors, but we kept the notes! Prereq Prereq A change Prereq Thursday, March 17, 2011
- 26. Then we Prereq Prereq implemented the A change prerequisites, one at a time... Prereq Thursday, March 17, 2011
- 27. Then we Prereq Prereq implemented the A change prerequisites, one at a time... Prereq Thursday, March 17, 2011
- 28. ...got new errors... ✘ ✘ ✘✘ ✘✘ ✘ ✘ Prereq Prereq A change Prereq Thursday, March 17, 2011
- 29. ...noted the new prerequisites... ✘ ✘ ✘✘ ✘✘ ✘ ✘ Prereq Prereq A change Prereq Thursday, March 17, 2011
- 30. ...noted the new prerequisites... ✘ ✘ ✘✘ Prereq✘✘ ✘ ✘ Prereq Prereq A change Prereq Thursday, March 17, 2011
- 31. ...noted the new prerequisites... Prereq✘✘ ✘ ✘ Prereq✘✘ ✘ ✘ Prereq Prereq A change Prereq Thursday, March 17, 2011
- 32. ...and reverted again Prereq✘✘ ✘ ✘ Prereq✘✘ ✘ ✘ Prereq Prereq A change Prereq Thursday, March 17, 2011
- 33. ...and reverted again Prereq Prereq Prereq Prereq A change Prereq Thursday, March 17, 2011
- 34. Picked the next leaf a.s.o... Prereq Prereq Prereq Prereq A change Prereq Thursday, March 17, 2011
- 35. ...until we could do a prerequisite w/o errors Prereq Prereq ✔ Prereq Prereq A change Prereq Thursday, March 17, 2011
- 36. We continued with all leaves... Prereq ✔ Prereq ✔ Prereq Prereq A change Prereq Thursday, March 17, 2011
- 37. Prereq ✔ Prereq ✔ Prereq ✔ Prereq ...getting transient A change prerequisites in place... Prereq Thursday, March 17, 2011
- 38. Prereq ✔ Prereq ✔ Prereq ✔ ✔ ...fulfilling Prereq prerequisites... A change Prereq Thursday, March 17, 2011
- 39. Prereq ✔ Prereq ✔ Prereq ✔ ✔ Prereq A change ...working the way Prereq ✔ back to the original change Thursday, March 17, 2011
- 40. Prereq ✔ Prereq ✔ Prereq ✔ ✔ Prereq A change Prereq ✔ In time, all prerequisites for the original change were in place... Thursday, March 17, 2011
- 41. Prereq ✔ Prereq ✔ Prereq ✔ ✔ Prereq A change ✔ Prereq ✔ The change was now easy to implement. Thursday, March 17, 2011
- 42. Prereq ✔ Prereq ✔ Prereq ✔ ✔ Prereq A change ✔ Prereq ✔ We’re done! Thursday, March 17, 2011
- 43. Mikado Method “rules” Thursday, March 17, 2011
- 44. Mikado Method “rules” Write down your goal -code or business Thursday, March 17, 2011
- 45. Mikado Method “rules” Write down your goal -code or business Seek things to try - note where it breaks Thursday, March 17, 2011
- 46. Mikado Method “rules” Write down your goal -code or business Seek things to try - note where it breaks Back out of broken code - it’s broken Thursday, March 17, 2011
- 47. Mikado Method “rules” Write down your goal -code or business Seek things to try - note where it breaks Back out of broken code - it’s broken Fix the prerequisites - recursively Thursday, March 17, 2011
- 48. Benefits Thursday, March 17, 2011
- 49. Benefits Always deliverable - from the main branch Thursday, March 17, 2011
- 50. Benefits Always deliverable - from the main branch Goal focus - do only the necessary Thursday, March 17, 2011
- 51. Benefits Always deliverable - from the main branch Goal focus - do only the necessary Visualize - memo and cooperation Thursday, March 17, 2011
- 52. The Mikado Method? Thursday, March 17, 2011
- 53. Thursday, March 17, 2011
- 54. ?!? Now, where’s the code...?!? Thursday, March 17, 2011
- 55. Lets do an example! Thursday, March 17, 2011
- 56. Welcome to Pasta Inc. Thursday, March 17, 2011
- 57. Coding: Exercise 1 Instructions: http://mikadomethod.wordpress.com/exercises/ Code: https://github.com/mikadomethod/kata-java Thursday, March 17, 2011
- 58. Questions? Thursday, March 17, 2011
- 59. Questions? Is this instead of refactorings or WELC? What about dynamically typed languages? How do I get started? What about design principles? Thursday, March 17, 2011
- 60. Forces when refactoring? Thursday, March 17, 2011
- 61. Forces when refactoring? http://commons.wikimedia.org/wiki/File:Maglev_june2005.jpg Thursday, March 17, 2011
- 62. Design principles! Move towards systems that are stable in the face of change Thursday, March 17, 2011
- 63. A selection of software principles Thursday, March 17, 2011
- 64. A selection of software principles • Don’t Repeat Yourself Thursday, March 17, 2011
- 65. A selection of software principles • Don’t Repeat Yourself • Class design principles Thursday, March 17, 2011
- 66. A selection of software principles • Don’t Repeat Yourself • Class design principles • Low coupling, high cohesion Thursday, March 17, 2011
- 67. A selection of software principles • Don’t Repeat Yourself • Class design principles • Low coupling, high cohesion • Immutability Thursday, March 17, 2011
- 68. A selection of software principles • Don’t Repeat Yourself • Class design principles • Low coupling, high cohesion • Immutability • Pure functions Thursday, March 17, 2011
- 69. Don’t Repeat Yourself - DRY Thursday, March 17, 2011
- 70. Don’t Repeat Yourself - DRY Code Thursday, March 17, 2011
- 71. Don’t Repeat Yourself - DRY Code Code Thursday, March 17, 2011
- 72. Don’t Repeat Yourself - DRY Code ✕ Code Thursday, March 17, 2011
- 73. Class design principles Thursday, March 17, 2011
- 74. Single Responsibility Principle - SRP Thursday, March 17, 2011
- 75. Single Responsibility Principle - SRP Thursday, March 17, 2011
- 76. Single Responsibility Principle - SRP ✕ Thursday, March 17, 2011
- 77. Open Closed Principle - OCP Thursday, March 17, 2011
- 78. Open Closed Principle - OCP Thursday, March 17, 2011
- 79. Liskow Substitution Principle - LSP Thursday, March 17, 2011
- 80. Liskow Substitution Principle - LSP Thursday, March 17, 2011
- 81. Liskow Substitution Principle - LSP Thursday, March 17, 2011
- 82. Liskow Substitution Principle - LSP is a Thursday, March 17, 2011
- 83. Liskow Substitution Principle - LSP is a Thursday, March 17, 2011
- 84. Interface Segregation Principle - ISP Thursday, March 17, 2011
- 85. Interface Segregation Principle - ISP Thursday, March 17, 2011
- 86. Interface Segregation Principle - ISP ✕ Thursday, March 17, 2011
- 87. Interface Segregation Principle - ISP ✕ http://commons.wikimedia.org/wiki/File:Pedalboard_%28995939579%29.jpg Thursday, March 17, 2011
- 88. Dependency Inversion Principle - DIP Thursday, March 17, 2011
- 89. Dependency Inversion Principle - DIP Thursday, March 17, 2011
- 90. S.O.L.I.D Thursday, March 17, 2011
- 91. S.O.L.I.D Single Responsibility Principle SRP Thursday, March 17, 2011
- 92. S.O.L.I.D Single Responsibility Principle SRP Open Closed Principle OCP Thursday, March 17, 2011
- 93. S.O.L.I.D Single Responsibility Principle SRP Open Closed Principle OCP Liskow Substitution Principle LSP Thursday, March 17, 2011
- 94. S.O.L.I.D Single Responsibility Principle SRP Open Closed Principle OCP Liskow Substitution Principle LSP Interface Segregation Principle ISP Thursday, March 17, 2011
- 95. S.O.L.I.D Single Responsibility Principle SRP Open Closed Principle OCP Liskow Substitution Principle LSP Interface Segregation Principle ISP Dependency Inversion Principle DIP Thursday, March 17, 2011
- 96. Package design principles Low coupling - High cohesion Thursday, March 17, 2011
- 97. Package design principles Low coupling - High cohesion Thursday, March 17, 2011
- 98. Package design principles Low coupling - High cohesion ✕ Thursday, March 17, 2011
- 99. Package design principles Low coupling - High cohesion ✕ Thursday, March 17, 2011
- 100. Thursday, March 17, 2011 Cohesion http://www.freedigitalphotos.net/images/view_photog.php?photogid=1970
- 101. Cohesion The Release Reuse Equivalency Principle - REP "The granule of release is the granule of reuse." http://www.freedigitalphotos.net/images/view_photog.php?photogid=1970 Thursday, March 17, 2011
- 102. Cohesion The Release Reuse Equivalency Principle - REP "The granule of release is the granule of reuse." The Common Reuse Principle - CRP "Classes that are used together are packaged together." http://www.freedigitalphotos.net/images/view_photog.php?photogid=1970 Thursday, March 17, 2011
- 103. Cohesion The Release Reuse Equivalency Principle - REP "The granule of release is the granule of reuse." The Common Reuse Principle - CRP "Classes that are used together are packaged together." The Common Closure Principle - CCP http://www.freedigitalphotos.net/images/view_photog.php?photogid=1970 "Classes that change together are packaged together." Thursday, March 17, 2011
- 104. Cohesion The Release Reuse Equivalency Principle - REP "The granule of release is the granule of reuse." The Common Reuse Principle - CRP "Classes that are used together are packaged together." The Common Closure Principle - CCP http://www.freedigitalphotos.net/images/view_photog.php?photogid=1970 "Classes that change together are packaged together." Thursday, March 17, 2011
- 105. Coupling Thursday, March 17, 2011
- 106. Coupling The Acyclic Dependencies Principle - ADP "The dependency graph of packages must have no cycles." Thursday, March 17, 2011
- 107. Coupling 142 Principles of packages Pkg Pkg The Acyclic Dependencies Principle - ADP "The dependency graph of packages must have no cycles." Pkg Pkg Pkg Figure 6.13: Cyclic dependencies are evil 142 Thursday, March 17, 2011
- 108. Coupling 142 Principles of packages Pkg Pkg The Acyclic Dependencies Principle - ADP "The dependency graph of packages must have no cycles." Pkg Pkg Pkg Figure 6.13: Cyclic dependencies are evil The Stable Dependencies Principle - SDP "Depend in the direction of stability." 142 Thursday, March 17, 2011
- 109. Coupling 142 Principles of packages Pkg Pkg The Acyclic Dependencies Principle - ADP "The dependency graph of packages must have no cycles." Pkg Pkg Pkg Figure 6.13: Cyclic dependencies are evil The Stable Dependencies Principle - SDP "Depend in the direction of stability." 142 Thursday, March 17, 2011
- 110. Coupling 142 Principles of packages Pkg Pkg The Acyclic Dependencies Principle - ADP "The dependency graph of packages must have no cycles." Pkg Pkg Pkg Figure 6.13: Cyclic dependencies are evil The Stable Dependencies Principle - SDP "Depend in the direction of stability." 142 The Stable Abstractions Principle - SAP "Abstractness increases with stability." Thursday, March 17, 2011
- 111. Coupling 142 Principles of packages Pkg Pkg The Acyclic Dependencies Principle - ADP "The dependency graph of packages must have no cycles." Pkg Pkg Pkg Figure 6.13: Cyclic dependencies are evil The Stable Dependencies Principle - SDP "Depend in the direction of stability." 142 The Stable Abstractions Principle - SAP "Abstractness increases with stability." Map of Old Town in Stockholm, 1733 Thursday, March 17, 2011
- 112. Immutability Thursday, March 17, 2011
- 113. Immutability Thursday, March 17, 2011
- 114. Pure functions Thursday, March 17, 2011
- 115. Pure functions f(x,y) = x + y Thursday, March 17, 2011
- 116. Coding: Exercise 2 Instructions: http://mikadomethod.wordpress.com/exercises/ Thursday, March 17, 2011
- 117. Coding: Exercise 2 Instructions: http://mikadomethod.wordpress.com/exercises/ Easy Enable reuse of PhysicalObject Thursday, March 17, 2011
- 118. Coding: Exercise 2 Instructions: http://mikadomethod.wordpress.com/exercises/ Easy Intermediate Two separate, minimal, deliverables for Enable reuse of PhysicalObject bouncing balls and solar system. Thursday, March 17, 2011
- 119. Coding: Exercise 2 Instructions: http://mikadomethod.wordpress.com/exercises/ Easy Intermediate Difficult Two separate, The domain logic is minimal, deliverables for Enable reuse of PhysicalObject compilable without Swing/AWT bouncing balls and solar dependencies system. Thursday, March 17, 2011
- 120. Thursday, March 17, 2011
- 121. Enable reuse of PhysicalObject Thursday, March 17, 2011
- 122. Create physics project Enable reuse of PhysicalObject Thursday, March 17, 2011
- 123. Move Create physics PhysicalObject to physics project projects Enable reuse of PhysicalObject Thursday, March 17, 2011
- 124. Make space depend on physics projects Move Create physics PhysicalObject to physics project projects Enable reuse of PhysicalObject Thursday, March 17, 2011
- 125. Pass stepSize (Space.seconds) to hitBy(..) Make space depend on physics projects Move Create physics PhysicalObject to physics project projects Enable reuse of PhysicalObject Thursday, March 17, 2011
- 126. Move PaintPhysicalObject to new SpaceGraphics class Pass stepSize (Space.seconds) to hitBy(..) Make space depend on physics projects Move Create physics PhysicalObject to physics project projects Enable reuse of PhysicalObject Thursday, March 17, 2011
- 127. Create SpaceGraphics class Move PaintPhysicalObject to new SpaceGraphics class Pass stepSize (Space.seconds) to hitBy(..) Make space depend on physics projects Move Create physics PhysicalObject to physics project projects Enable reuse of PhysicalObject Thursday, March 17, 2011
- 128. Create Inject PhysicalObject po SpaceGraphics class into PaintPhysicalObject Move PaintPhysicalObject to new SpaceGraphics class Pass stepSize (Space.seconds) to hitBy(..) Make space depend on physics projects Move Create physics PhysicalObject to physics project projects Enable reuse of PhysicalObject Thursday, March 17, 2011
- 129. Create ✔ Inject PhysicalObject po SpaceGraphics class into PaintPhysicalObject Move PaintPhysicalObject to new SpaceGraphics class Pass stepSize (Space.seconds) to hitBy(..) Make space depend on physics projects Move Create physics PhysicalObject to physics project projects Enable reuse of PhysicalObject Thursday, March 17, 2011
- 130. Create ✔ ✔ Inject PhysicalObject po SpaceGraphics class into PaintPhysicalObject Move PaintPhysicalObject to new SpaceGraphics class Pass stepSize (Space.seconds) to hitBy(..) Make space depend on physics projects Move Create physics PhysicalObject to physics project projects Enable reuse of PhysicalObject Thursday, March 17, 2011
- 131. Create ✔ ✔ Inject PhysicalObject po SpaceGraphics class into PaintPhysicalObject Move PaintPhysicalObject to new SpaceGraphics class ✔ Pass stepSize (Space.seconds) to hitBy(..) Make space depend on physics projects Move Create physics PhysicalObject to physics project projects Enable reuse of PhysicalObject Thursday, March 17, 2011
- 132. Create ✔ ✔ Inject PhysicalObject po SpaceGraphics class into PaintPhysicalObject Move PaintPhysicalObject to new SpaceGraphics class ✔ Pass stepSize ✔ (Space.seconds) to hitBy(..) Make space depend on physics projects Move Create physics PhysicalObject to physics project projects Enable reuse of PhysicalObject Thursday, March 17, 2011
- 133. Create ✔ ✔ Inject PhysicalObject po SpaceGraphics class into PaintPhysicalObject Move PaintPhysicalObject to new SpaceGraphics class ✔ Pass stepSize ✔ (Space.seconds) to hitBy(..) Make space depend on physics projects Move Create physics project ✔ PhysicalObject to physics projects Enable reuse of PhysicalObject Thursday, March 17, 2011
- 134. Create ✔ ✔ Inject PhysicalObject po SpaceGraphics class into PaintPhysicalObject Move PaintPhysicalObject to new SpaceGraphics class ✔ Pass stepSize ✔ (Space.seconds) to hitBy(..) Make space depend on physics ✔ projects Move Create physics project ✔ PhysicalObject to physics projects Enable reuse of PhysicalObject Thursday, March 17, 2011
- 135. Create ✔ ✔ Inject PhysicalObject po SpaceGraphics class into PaintPhysicalObject Move PaintPhysicalObject to new SpaceGraphics class ✔ Pass stepSize ✔ (Space.seconds) to hitBy(..) Make space depend on physics ✔ projects Move ✔ Create physics project ✔ PhysicalObject to physics projects Enable reuse of PhysicalObject Thursday, March 17, 2011
- 136. Create ✔ ✔ Inject PhysicalObject po SpaceGraphics class into PaintPhysicalObject Move PaintPhysicalObject to new SpaceGraphics class ✔ Pass stepSize ✔ (Space.seconds) to hitBy(..) Make space depend on physics ✔ projects Move ✔ Create physics project ✔ PhysicalObject to physics projects Enable reuse of PhysicalObject ✔ Thursday, March 17, 2011
- 137. Thanks!! Daniel Brolund @danielbrolund Ola Ellnestam @ellnestam #mikadomethod @mikadomethod http://mikadomethod.org http://mikadomethod.wordpress.com http://groups.google.com/group/mikado-method Thursday, March 17, 2011