Primer on the 4 Rules of Simple Design

A short introduction to the 4 Rules of Simple Design given at Boulder Ruby in 2015 and 2016.

Transcript

1. Primer on the 4 Rules of Simple Design Marty Haught @mghaught
2. Origin • Introduced by Kent Beck pre 2000 • via Extreme Programming (XP) • Associated with “Do the simplest thing that could possibly work.”
3. Corey Haines http://bit.ly/4rules-boulderruby $11.99 • via Code retreats • Conway’s Game of Life
4. The Rules 1. Tests pass 2. Expresses intent 3. No duplication 4. Small
5. 1. Tests Pass • Need to verify that your code/system works • Automated tests are the fastest way to verify
6. 2. Expresses Intent • Intention revealing • You can quickly look at it and know what it does • Not bad naming, unclear or inaccurate • Does the method/variable match the language you use to describe it?
7. 3. No Duplication • DRY - Don’t Repeat Yourself • Commonly thought of as repetition in code structure (lines of code) • Also knowledge duplication • "Every piece of knowledge should have one and only one representation."
8. 4. Small • No extraneous parts to the code • Does everything there have a purpose? • Is it still being used? • Did I extract too far?
9. Resources • Corey’s Book: http://bit.ly/4rules-boulderruby • XP wiki: http://c2.com/cgi/wiki?XpSimplicityRules • JB Rainsberger: http://www.jbrains.ca/permalink/ the-four-elements-of-simple-design