Class 4: Cathedral/Bazaar Discussion

Notes for 5/30/2013

Transcript

1. Cathedral/Bazaar Discussion Class Four: May 30, 2013
2. The  Cathedral  and  the  Bazaar   Discussion •What  are  some  of  the  differences  between  cathedral   and  bazaar  development  styles? •Why  did  Eric  Raymond  start  working  on  this  mail   program  in  the  first  place? •What’s  the  dis?nc?on  in  coding  between  original   crea?ons  and  code  reuse? •In  his  opinion,  why  is  it  important  to  “release  early  and   release  oDen”? •Why  are  “customers”  (or  users)  important?
3. Cathedral-­‐Bazaar  Lessons Every  good  work  of  soDware  starts  by  scratching  a   developer's  personal  itch. Good  programmers  know  what  to  write.  Great  ones  know   what  to  rewrite  (and  reuse). • Neither  of  us  was  “original”  in  the  roman?c  way  people  think  is  genius.  But   then,  most  science  and  engineering  and  soDware  development  isn't  done   by  original  genius,  hacker  mythology  to  the  contrary. • It's  fairly  clear  that  one  cannot  code  from  the  ground  up  in  bazaar  style.   One  can  test,  debug  and  improve  in  bazaar  style,  but  it  would  be  very  hard   to  originate  a  project  in  bazaar  mode…  Your  nascent  developer  community   needs  to  have  something  runnable  and  testable  to  play  with. “Plan  to  throw  one  away;  you  will,  anyhow.” Or,  to  put  it  another  way,  you  oDen  don't  really  understand  the  problem  un?l   aDer  the  first  ?me  you  implement  a  solu?on.  The  second  ?me,  maybe  you   know  enough  to  do  it  right.  So  if  you  want  to  get  it  right,  be  ready  to  start   over  at  least  once.
4. Cathedral-­‐Bazaar  Lessons When  you  lose  interest  in  a  program,  your  last  duty  to  it   is  to  hand  it  off  to  a  competent  successor. Trea?ng  your  users  as  co-­‐developers  is  your  least-­‐hassle   route  to  rapid  code  improvement  and  effec?ve   debugging. • “I'm  basically  a  very  lazy  person  who  likes  to  get  credit  for  things   other  people  actually  do.”  -­‐  Linus  Torvalds Release  early.  Release  oDen.  And  listen  to  your   customers.
5. Cathedral-­‐Bazaar  Lessons Given  a  large  enough  beta-­‐tester  and  co-­‐developer  base,   almost  every  problem  will  be  characterized  quickly  and   the  fix  obvious  to  someone. If  you  treat  your  beta-­‐testers  as  if  they're  your  most   valuable  resource,  they  will  respond  by  becoming  your   most  valuable  resource. The  next  best  thing  to  having  good  ideas  is  recognizing   good  ideas  from  your  users.  Some?mes  the  laZer  is   beZer.
6. Linus’s  Law:  A  Core  Difference Or,  less  formally,  “Given  enough  eyeballs,  all  bugs  are  shallow.” …Every  problem  “will  be  transparent  to  somebody”.  Linus  demurred  that  the   person  who  understands  and  fixes  the  problem  is  not  necessarily  or  even   usually  the  person  who  first  characterizes  it.  “Somebody  finds  the  problem,”   he  says,  “and  somebody  else  understands  it.  And  I'll  go  on  record  as  saying   that  finding  it  is  the  bigger  challenge.” In  the  cathedral-­‐builder  view  of  programming,  bugs  and  development   problems  are  tricky,  insidious,  deep  phenomena.  It  takes  months  of  scru?ny   by  a  dedicated  few  to  develop  confidence  that  you've  winkled  them  all  out.   Thus  the  long  release  intervals,  and  the  inevitable  disappointment  when   long-­‐awaited  releases  are  not  perfect. In  the  bazaar  view,  on  the  other  hand,  you  assume  that  bugs  are  generally   shallow  phenomena—or,  at  least,  that  they  turn  shallow  preZy  quickly  when   exposed  to  a  thousand  eager  co-­‐developers  pounding  on  every  single  new   release.  Accordingly  you  release  oDen  in  order  to  get  more  correc?ons,  and   as  a  beneficial  side  effect  you  have  less  to  lose  if  an  occasional  botch  gets   out  the  door.
7. Cathedral-­‐Bazaar  Lessons ODen,  the  most  striking  and  innova?ve  solu?ons  come   from  realizing  that  your  concept  of  the  problem  was   wrong. • When  you  hit  a  wall  in  development—when  you  find  yourself  hard   put  to  think  past  the  next  patch—it's  oDen  ?me  to  ask  not  whether   you've  got  the  right  answer,  but  whether  you're  asking  the  right   ques?on.  Perhaps  the  problem  needs  to  be  reframed. "Perfec?on  (in  design)  is  achieved  not  when  there  is   nothing  more  to  add,  but  rather  when  there  is  nothing   more  to  take  away."
8. Cathedral-­‐Bazaar  Lessons Any  tool  should  be  useful  in  the  expected  way,  but  a   truly  great  tool  lends  itself  to  uses  you  never  expected. • Binder  Clip! When  wri?ng  gateway  soDware  of  any  kind,  take  pains   to  disturb  the  data  stream  as  liZle  as  possible—and   never  throw  away  informa?on  unless  the  recipient   forces  you  to!
9. Cathedral-­‐Bazaar  Lessons To  solve  an  interes?ng  problem,  start  by  finding  a   problem  that  is  interes?ng  to  you. • That  is,  while  coding  remains  an  essen?ally  solitary  ac?vity,  the   really  great  hacks  come  from  harnessing  the  aZen?on  and   brainpower  of  en?re  communi?es.  The  developer  who  uses  only   his  or  her  own  brain  in  a  closed  project  is  going  to  fall  behind  the   developer  who  knows  how  to  create  an  open,  evolu?onary   context  in  which  feedback  exploring  the  design  space,  code   contribu?ons,  bug-­‐spo_ng,  and  other  improvements  come  from   hundreds  (perhaps  thousands)  of  people. Provided  the  development  coordinator  has  a   communica?ons  medium  at  least  as  good  as  the   Internet,  and  knows  how  to  lead  without  coercion,   many  heads  are  inevitably  beZer  than  one.
10. On  Deadlines  /  On  Happiness When  programmers  are  held  both  to  an  immutable   feature  list  and  fixed  drop-­‐dead  date,  quality  goes  out   the  window  and  there  is  likely  a  colossal  mess  in  the   making. • Development  Methodologies Human  beings  generally  take  pleasure  in  a  task  when  it   falls  in  a  sort  of  op?mal-­‐challenge  zone;  not  so  easy  as   to  be  boring,  not  too  hard  to  achieve.  A  happy   programmer  is  one  who  is  neither  underu?lized  nor   weighed  down  with  ill-­‐formulated  goals  and  stressful   process  fric?on.  Enjoyment  predicts  efficiency.