500 Lines or Less

"What I cannot create, I do not understand."

-- Richard Feynman

This is the source for the book 500 Lines or Less, the fourth in the Architecture of Open Source Applications series. As with other books in the series, all written material will be covered by the Creative Commons - Attribution license, and all code by the MIT License: please see the license description for details. In addition, all royalties from paid-for versions will all go to Amnesty International.

The production of this book has been made possible by the financial support of PagerDuty.

Mission

Every architect studies family homes, apartments, schools, and other common types of buildings during her training. Equally, every programmer ought to know how a compiler turns text into instructions, how a spreadsheet updates cells, and how a database efficiently persists data.

Previous books in the AOSA series have done this by describing the high-level architecture of several mature open-source projects. While the lessons learned from those stories are valuable, they are sometimes difficult to absorb for programmers who have not yet had to build anything at that scale.

"500 Lines or Less" focuses on the design decisions and tradeoffs that experienced programmers make when they are writing code:

• Why divide the application into these particular modules with these particular interfaces?
• Why use inheritance here and composition there?
• How do we predict where our program might need to be extended, and how can we make that easy for other programmers?

Each chapter consists of a walkthrough of a program that solves a canonical problem in software engineering in at most 500 source lines of code. We hope that the material in this book will help readers understand the varied approaches that engineers take when solving problems in different domains, and will serve as a basis for projects that extend or modify the contributions here.

Contributors

Name	Affiliation	Project	Online	GitHub	Email (if you choose)
Mike DiBernardo	freelance	editorial	@mdibernardo mikedebo.ca	MichaelDiBernardo	[email protected]
Amy Brown	indie	editorial	amyrbrown.ca @amyrbrown	amyrbrown	[email protected]
Dustin Mitchell	Mozilla	cluster		djmitche	[email protected]
Audrey Tang	g0v.tw, Socialtext, Apple	spreadsheet	@audreyt	audreyt	[email protected]
Greg Wilson	Mozilla	web-server	@gvwilson	gvwilson	[email protected]
Taavi Burns	Previously at Points, now at PagerDuty	data-store	@jaaaarel	taavi	[email protected]
Guido van Rossum	Dropbox	crawler	@gvanrossum	gvanrossum	[email protected]
A. Jesse Jiryu Davis	MongoDB	crawler	@jessejiryudavis	ajdavis	[email protected]
Erick Dransch	Upverter	Modeller	@ErickDransch	EkkiD	[email protected]
Ned Batchelder	edX	templating engine	nedbatchelder.com @nedbat	nedbat	[email protected]
Leah Hanson	Google	static analysis	@astrieanna	astrieanna	[email protected]
Christian Muise	University of Melbourne	flow-shop	@cjmuise	haz	[email protected]
Marina Samuel	Mozilla	ocr	www.marinasamuel.com @emtwos	emtwo	[email protected]
Cate Huston		Image Filter app	www.accidentallyincode.com/ @catehstn	catehstn	[email protected]
Yoav Rubin	Microsoft	In-memory functional database	@yoavrubin	yoavrubin
Dessy Daskalov	Nudge Rewards	Pedometer	www.dessydaskalov.com @dess_e	dessy	[email protected]
Carl Friedrich Bolz	King's College London	object model	cfbolz.de @cfbolz	cfbolz	[email protected]
Jessica Hamrick	University of California, Berkeley	sampler	www.jesshamrick.com @jhamrick	jhamrick	[email protected]
Allison Kaptur	Hacker School	byterun	@akaptur	@akaptur	[email protected]
Daniel Rocco	BrightLink Technology	contingent	@drocco007	drocco007	[email protected]
Brandon Rhodes	Dropbox	contingent	@brandon_rhodes	brandon-rhodes	[email protected]
Dann Toliver	Bento Box	dagoba	danntoliver.com @dann	dxnn	[email protected]
Malini Das	Twitch	ci	malinidas.com @malinidas	malini