Pair programming

pair programming

twitter : @JonJaggeremail : [email protected]

blog : http://jonjagger.blogspot.co.uk/charity : http://cyber-dojo.org

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a seldom questioned view of programming - a view which this book will spend a great deal of time questioning. That view is that programming is an individual activity...

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Written 1969 Published 1971

Silver Anniversary 1994 Golden Anniversary 2019

longest continuously in-print book on software

development?

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devs who say they work alone don't

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pairing and getting unstuck

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rubber-duck debugging

https://en.wikipedia.org/wiki/Rubber_duck_debugging

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silenttalking

images are representative only

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lifesize cardboard cutouts!

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pairing and perseverance

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what 's the longest lived

bug?

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queen termites can live

50 years!

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time

6-12 months0 months

RIP

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if you're going through hell, keep going

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pairing and productivity

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in my experience, pair programming is

more productive than dividing the work between

two programmers and then integrating the

results

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programmers admit to working harder and

smarter on programs because they do not want

to let their partner down

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pairs spent about 15% more time on the program than the individuals*

the resulting code has about 15% fewer defects

the pairs consistently implemented the same functionality in fewer lines of code

most of the programmers enjoyed programming

collaboratively

http://collaboration.csc.ncsu.edu/laurie/Papers/ieeeSoftware.PDF

strengthening the case for pair programming

Laurie WilliamsRobert Kessler

Ward CunninghamRon Jeffries

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An experiment by Temple University Professor Nosek studied 15 full-time, experienced programmers

working for 45 minutes on a challenging problem, important to their organization, in their own

environment, and with their own equipment. Five worked individually, ten worked collaboratively in five pairs. Conditions and materials used were the same for both the experimental (team) and control

(individual) groups.

Nosek, J. T. (1998). The Case for Collaborative Programming. Communications of the ACM. March 1998: 105-108.

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All the teams outperformed the individual programmers, enjoyed the problem-solving

process more, and had greater confidence in their solutions... producing better algorithms

and code in less time (40%)

Results statistically significant using two-sidedt-test.

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if pairing increases productivity

why is it rare?

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pairing is rare because working solo is common!

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"locking" occurs whenever a situation

creates an environment favorable for

maintaining that situation...

locking occurs in all sorts of systems...

especially... social

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? different keyboards ? different editors ? table design ? room layout ? number of computers ? tools ? individual assessments ? languages ? expertise

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most people resist transitioning to pair programming – it involves breaking old habits and being more communicative and collaborative than we’ve been conditioned to be

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pairs spent about 15% more time on the program than the individuals*

the resulting code has about 15% fewer defects

the pairs consistently implemented the same functionality in fewer lines of code

most of the programmers enjoyed programming

collaboratively

for the first assignment pairs took 60% more programmer hours to complete the assignment

*

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transitioning to pairing is not easy

give it at least 3 weeks

it gets worse before it gets better

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XP

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name the XP values

4 in edition 1 5 in edition 2

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Simplicity Communication Feedback Courage! Trust

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pairing and communication

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pair programming works for XP because it encourages communication

XP is a communal software development discipline.

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we believe pair programming is an integral part

of XP

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pairing doesn't really work if you don't talk!

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"at first I found it hard

to verbalize my thoughts"

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pairing and courage

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if people program solo they are more likely to make mistakes, more likely to

overdesign, more likely to blow off the other practises, particularly under pressure

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under stress, people revert to earlier behaviour, no matter how badly that behaviour has worked in the past

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programmers admit to working harder and

smarter on programs because they do not want

to let their partner down

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Studies of Independence and Submission to Group Pressure.

A Minority of One Against a Unanimous Majority

Solomon Asch

Psychological Monographs, 7, Series No. 416, 1956.

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7 confederates 1 subject

https://en.wikipedia.org/wiki/Asch_conformity_experiments

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18 trialsin trial 1 and trial 2 the

7 confederates and the subject gave the obviously right answer

in the remaining 16 trials the 7 confederates gave the wrong

answer 12 times

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75% of subjects gave incorrect answer in at least 1 trial

subject conformed to the incorrect answer in all 12 trials

36% of the time

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variationpresence of 1 true confederate decreased subjects conformity

to the incorrect answer by 75%

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pairing and feedback

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it is a well-known psychological principle that in order to maximize the rate of learning, the subject must be fed back information on how well or poorly he is doing

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the average adult learns very little if

left to his own devices

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we are all lousy self evaluators

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?% of high school seniors believe their leadership skills are below average

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2% of high school seniors believe their leadership skills are below average

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I am the World's leading expert

on the Dunning-Kruger effect!

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pairing and

learning

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the requirement to develop capability cannot be met adequately by a single person. We learn much faster and much better with the active cooperation of others

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learning from success

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learning from failure only has meaning when we know what we mean by success

Kevlin Henney

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i have not failed i've just found

1000 ways that won't work

Thomas Edison

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success == invent an incandescent light bulb that lasts

one hour

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recording pairs clock faces

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picking pairs randomly!

helps reduce locking

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pairing and risk

helps reduce truck/bus number

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pairing and risk

also known as the lottery number

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pairing and interruptionspairs are very resistant to interruptions

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pairing and interviewing

teamwork characteristics... cannot be determined if you interview ... one at a time.

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pairing and practice

I felt it was unwise to allow players to practice by

themselves. Always I wanted them to be interacting with

their teammates.

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pairing and ping-pong

http://c2.com/cgi/wiki?PairProgrammingPingPongPattern

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pairing and refactoring

Wibble * p = new WIbble(); if (p == NULL) ....

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if driver always writes definitions before use suggest

writing use before definition

pairing and observing

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navigator reads ALPHA in code/comment but

driver says BETA when describing ALPHA

pairing and observing

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triple programming

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the pair results were also more consistent, while the individuals varied more about the mean

pairing and consistency

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pairing and scaling

having more than nine members requires too much coordination

Scrum Guide

having more than nine pairs requires too much coordination

What about...

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repairing

in http://cyber-dojo.org pairs easily cope with repairing every 5 minutes!

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pairing and becoming a

team

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if egoless programming is used, everyone in the group will have the opportunity to examine the work of everyone else at some time, thereby tending to prevent the establishment of strong hierarchy p72

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widespread use of pair programming involves a

cultural shift in values of the organization - away from

individual and toward team recognition and goals

thanks for listening

twitter : @JonJaggeremail : [email protected]

blog : http://jonjagger.blogspot.co.uk/charity : http://cyber-dojo.org