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

Technical Reviewers

Amber Yust	Andrew Gwozdziewycz	Andrew Kuchling
Andrew Svetlov	Andy Shen	Anton Beloglazov
Ben Trofatter	Borys Pierov	Carise Fernandez
Charles Stanhope	Chris Atlee	Chris Seaton
Cyryl Płotnicki-Chudyk	Dan Langer	Dan Shapiro
David Pokorny	Eric Bouwers	Frederic De Groef
Graham Lee	Gregory Eric Sanderson	James O'Beirne
Jan de Baat	Jana Beck	Jessica McKellar
Jo Van Eyck	Joel Crocker	Johan Thelin
Johannes Fürmann	John Morrissey	Joseph Kaptur
Josh Crompton	Joshua T. Corbin	Kevin Huang
Maggie Zhou	Marc Towler	Marcin Milewski
Marco Lancini	Mark Reid	Matthias Bussonnier
Max Mautner	Meggin Kearney	Mike Aquino
Natalie Black	Nick Presta	Nikhil Almeida
Nolan Prescott	Paul Martin	Piotr Banaszkiewicz
Preston Holmes	Pulkit Sethi	Rail Aliiev
Ronen Narkis	Rose Ames	Sina Jahan
Stefan Turalski	William Lachance