1. Pair Programming
You will never work alone again!
Naresh Jain
naresh@agilefaqs.com
Licensed Under Creative Commons by Naresh Jain
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2. What is Pair Programming ?
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3. Video of a Sniper team working together
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4. What did we see ?
Two guys working on the same task
Both have the same target
Both have different expertise
One executes the task
The other watches for external factors, evaluates the situation,
corrects him and validates success after execution
Two guys working as a team
Licensed Under Creative Commons by Naresh Jain
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5. What is Pair Programming ?
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6. src: ThoughtWorks India
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7. src: ThoughtWorks India
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8. Pairing
Station
src: ThoughtWorks India
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9. Driver
Pairing
Station
src: ThoughtWorks India
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10. Driver
Navigator
Pairing
Station
src: ThoughtWorks India
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11. Next
line
of
code,
syntax,
API,
class
under
dev
Driver
Navigator
Pairing
Station
src: ThoughtWorks India
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12. are
we
in
the
right
direction?,
Next
line
of
code,
requirements,
alternatives,
syntax,
API,
next
test
case,
class
under
dev
impact
Driver
Navigator
Pairing
Station
src: ThoughtWorks India
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13. Isn't it a waste ?
Two developers will do the work of one
Junior guys will slow down seniors
Less work will get done
My cost will double
Why would I put two people on a job that just one can do?
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14. TICO TICO (Guitar Four-Hand Exchanging) Video
http://www.youtube.com/watch?v=CcsSPzr7ays
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15. 9

16. 10

17. 11

18. 12

19. How does it Help?
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20. Continuous Review
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21. Less Defects
Defects caught early
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22. Improvement in the
Quality of the Design
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23. Better Problem Solving
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24. More Economical
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25. “Pair-Pressure”
ensures timely delivery
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26. Rapid Hands-on
Approach to Learning
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27. Better Induction of
new Team Members
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28. Better Induction of
new Team Members
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29. Saved Effort on Intra-
Team Documentation
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30. Less Distraction leading
to Higher Productivity
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31. Improved Satisfaction
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32. Sustainable Pace:
Helps you slow down
and think
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33. Better Team Building
and Communication
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34. Project Management:
Risk Mitigation Strategy
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35. We are in the business of building software and this process
requires craft and skill, rather than a series of manual steps.
Programming requires lot of thinking, creating abstractions,
figuring out the logic and trying out things.
An evolutionary, iterative and collaborative process.
Its a lot more than just typing code.
(Using the keyboard or even worse, using the mouse)
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36. A Normal Pair Programming Video
http://www.youtube.com/watch?v=q-QWdFa4awI
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37. Consider the following...
An experiment on Pair Programming
at University of Utah
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38. Cost and savings
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39. Cost and savings
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40. Cost of fixing defects
Cost
of
defect
Time
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41. Cost of fixing defects
Cost
of
defect
Time
“IBM reported spending about $250 million repairing and reinstalling
fixes to 30,000 customer-reported problems.
That is over $8,000 for each defect!”
- “A Discipline for Software Engineering”, 1995, Humphrey, W.S.
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42. Incorporating pair-programming into a
software development process will help
yield software products of better
quality in less time with happier,
more confident programmers!
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43. Points of resistance
Things to watch out for...
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44. Difficulty in convincing
stakeholders to let two
people work on one task
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45. Everyone settles down
into a “Comfort Zone”
Pairing would disrupt it
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46. Strong Code Ownership
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47. People Who Don’t Care
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48. Developers not involved
in Estimation and Planning
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49. Inconsistent
Workstation Setup
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50. Small Work Area
(Cubicles)
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51. Techniques of Pairing
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52. Ping-Pong Pairing
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53. Keyboard n Mice Pairing
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54. Selective Pairing
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55. Cross functional Pairing
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56. Distributed Pairing
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57. Tips n Tricks
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58. Pairing Stations
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59. Pair Rotation with
Pair Hinging
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60. Promiscuous
Pair Programming
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61. Pairing Round
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62. Pair Stairs
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63. Spikes
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64. Pairing Smells
Things to Watch out for...
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65. Pair Programming Anti Patterns Video
http://www.youtube.com/watch?v=ReuFZYtGeCc
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66. No Pair Rotation
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67. Only one person driving
Distracted Pair
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68. Selective Pairing closer
to a Release
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69. Manager decides the Pairs
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70. When its not necessary?
Tasks which involve Mundane Work (may be)
Trivial bug fixes like Typos
One person in the Pair is Sick
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71. F.A.Q.s
How do you do estimation? Its 2 people working on one task now.
How do you do performance reviews for individuals?
Can we keep it optional for some people on a team?
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72. References
The Costs and Benefits of Pair Programming
- Laurie Williams & Alistair Cockburn
Strengthening the Case for Pair-Programming
- Laurie Williams, Robert R. Kessler, Ward Cunningham & Ron Jeffries
On the Economic Feasibility of Pair Programming
- Hakan Erdogmus & Laurie Williams
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73. Thank You!
Questions?
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