Pair Programming: What is it?

1
Pair Programming What is it?

• Two programmers working side-by-side,
  collaborating on the same design, algorithm, code
  or test
• One programmer, the driver, has control of the
  keyboard/mouse and actively implements the
  program
• The other programmer, the observer, continuously
  observes the work of the driver to identify
  tactical (syntactic, spelling, etc.) defects and
  also thinks strategically about the direction of
  the work
• On demand, the two programmers can brainstorm any
  challenging problem
• Because the two programmers periodically switch
  roles, they work together as equals to develop
  software-- Laurie Williams, North Carolina
  State University Computer Science

2
Pair Programming Why do it?

• You learn faster when a partner is helping double
  check
• Two sets of eyes are more likely to notice errors
  than one set
• You learn better when
• a partner is helping you understand
• you are challenging your partner to master the
  material
• Pair programming is a real-life technique, part
  of the disciplined methods called Extreme
  Programming
• One study
• Paired programmers are only 15 slower than two
  independent individual programmers
• But produce 15 fewer bugs
• Since testing and debugging are often many times
  more costly than initial programming, this is an
  impressive result
• http//www.economist.com/displayStory.cfm?Story_ID
  779429

3
Challenges of Pair Programming

• What are some problems that partners (let's call
  them Ye and Seema) may experience?
• Seema dominates the project and does not let Ye
  do half the work
• Seema decides that Ye cannot write code and so
  assigns everything else besides the code to him
• Ye is passive and plays a "keep the other person
  company" role
• Ye misses class without alerting Seema or the
  professor
• Seema is unavailable outside of class
• Seema believes that Ye's performance will hurt
  Seemas grade

4
Dos of Pair Programing

• Both partners sit behind a single computer
• Exception Use the second computer effectively
  for reading the instructions and responding
• However, both partners must be looking at the
  same computer screen at any given time
• Share the typing duties
• Both partners think! Both partners solve the
  problem!
• When not typing, validate what your partner
  should be typing
• Both partners understand each step completely
  before continuing
• It is
• good to take time to teach your partner some
  things
• not good to spend the entire session teaching
  your partner
• Try to choose a partner with similar skill and
  comfort-level

5
Continuing work outside class

• When you are in class
• Identify and schedule (exact) times to meet face
  to face
• Identify ways to contact your partner (email,
  phone, etc)
• Do not waste your partner's time
• Show up on time and stay focused for scheduled
  meetings
• Do not work on the project without your partner
• Pair programming is not team programming

You will do most of your projects using Pair
Programming we insist that you do it
effectively!