hacker101/102

code4lib 2010 preconferenceAsheville, NC, USA 2010-02-21

i. intro

why are we here?

learn to hack?

...not exactly

we work in librariesso we can

help people

we hack to help ourselves

help others

what’s a good hacker?

languages?standards?

jargon?math?logic?

frameworks?

nope!

a good hackerknows

when to ask for help

a good hackerknows

how to ask for help

a good hackerknows how

to help other hackers

a good hackerknows other hackers

to ask for help

when to askhow to ask

how to answerwhom to ask

i’m herebecause i want

to be able to ask you

when to ask?

thirty minute rule

for today:three minute rule

how to ask?see “How to ask

questions the smart way”

we’ll get startedtogether

basics in Processingregexes in JavaScript

glue it together in Python

explore on your own

get comfortableasking for help

ii. the basics

Processing

canvas, grid, points

200

400

300200

lines, rects, ellipses

start

end

syntax, functions, errors

don’t be afraidto break stuff

variables, loops

test

initial value

type “integer”

increment

repeatingactions

every lang has loops

• for (a=blah, a<foo, a=a+bar) {...}

• for each (foo in blah) {...}

• for i in range(20): ...

• while (foo != bar) do {...}

• next, continue, break

more variables, loops

even more variables, loops

explore on your own

iii. functions, objects,the main loop

why functions?

setup, draw, void

function structure

RETURN_TYPE FUNCTION_NAME ([var a, ...]) {...statements...}

setup, draw

•void: returns nothing (into the void!)

•setup: prep stuff

•draw: the “animation loop” or “main”

different kinds of “main”

• Processing: draw() is like an animation “cell”

• in a GUI: the user feedback loop

• command-line app: parse args, then main()

• web app: the user feedback loop

setup, draw, void

we canwrite this better

setup, draw, void

see the problem?

setup, draw, void

DRYDon’t Repeat Yourself

a littlebetter

moretask

specific

adddelay(10);

nowtry this

initialization

no loop!

if/elsei.e.

“conditional”

•draw() is already a loop; why another?

•“i” becomes state

•tightens up draw()

what about objects?

objecti

fied

• it says what it is

• it removes a lot of repeated noise

• it’s kinda overkill here

•we don’t use rp1 and rp2 again

• design a matter of taste

• sometimes things should be called what they mean

• sometimes an “int i” is just an “int i”

• think about what you’ll understand later

no single answer

explore on your own