Chapter 11: Plan to Throw One Away

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Chapter 11Plan to Throw One Away

• By Nate Loontjer
• 03/05/2002

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Programmers Have Not Learned From Other Industries

• Automotive, Chemical, etc. use pilot plants to
  test design concepts.
• Pilot plants are used to find and correct
  problems before the final plant or product is
  implemented.

• Systems programmers expect the first product to
  be correct and useable.
• The first product is delivered to customers and
  subsequent bugs/features are worked out later.

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• Plan to throw one away you will, anyhow.

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How to Prepare a System For Change

• Modularization
• Subroutines
• Complete definition of interfaces
• Complete Documentation

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Two Steps Forward, One Back

• Program maintenance begins after delivery.
• Old bugs are fixed, new features are introduced.
• New features introduce new bugs.

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One Step Forward, One Back

• At some point, bugs from new and old features
  become so entwined with the system that it is
  impossible to root them out, and a new system
  will need to be developed from scratch. The new
  system should take advantage of new hardware,
  configurations, and user requirements.