The Even Darker Art of Rails Engines

The Even Darker Art of Rails Engines

Given at RailsConf 2009

Acd62030df551952268e84c8fff26a5b?s=128

lazyatom

May 05, 2009
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  1. The Even-Darker Art of Rails Engines

  2. @lazyatom

  3. github.com/lazyatom/engines

  4. Rails 2.3

  5. history

  6. November 2005

  7. it’s distracting!

  8. reuse is overrated!

  9. Evil! Evil! Evil! Evil! Evil! Evil! Evil! Evil! Shit!

  10. eek!

  11. appable_plugins

  12. desert

  13. merb slices?

  14. None
  15. engines

  16. !"#$%&!"#$'#(%&$#)&!"#$%&*$+,#-.!) !"#$%&'() $$*%&'()$++,$-'%!.%&'()./0#'12%)/'0 "0! 3$405/0"6$%1"$7-(5/06$8/)9$%0$%77:$!/1";)'1<= !"#$"05/0"> $$9%6.%77.!/1";)'1<> "0! 3$?")(106$)1("$/#$)9"$"05/0"$69/76$8/)9$%$1'()/05$#/-" !"#$1'()"!>

    $$@/-"="A/6)>B1'()/05.#/-"C "0! !"#$D/"8.7%)9 $$@/-"=E'/0B!/1";)'1<F$G%77GF$GD/"86GC "0!
  17. app/controllers/ models/ helpers/ views/ metal/

  18. *$+,#-&"**&23-'!3$$(!&*$+,#-523-'!3$$(!.!) ;-%66$H-(5/0I'0)1'--"1/0/1**$#2"'#3-43-'!3$$(! $$!"#$/0!"A $$$$1"0!"1$J)"A)$,K$LM"--'F$H-(5/0NL $$"0! "0!

  19. 9"-7"1$J%-- won’t load from your plugin

  20. Ticket #1905

  21. config/routes.rb

  22. O;)/'0I'0)1'--"1JJ?'()/05JJ?'()"6=!1%8$!'$+2%7+ $$2%7=;'00";)$G:7%)9GF$J;'0)1'--"1$,K$L7-(5/0LF$ $$$$$$$$$$$$$$$$$$$$$$$J%;)/'0$,K$L/0!"AL "0! *$+,#-&23-6#,&!3+'(%.!)

  23. top precedence

  24. O;)/'0I'0)1'--"1JJ?'()/05JJ?'()"6=!1%8$!'$+2%7+ $$2%7=;'00";)$G:7%)9GF$J;'0)1'--"1$,K$L7-(5/0LF$ $$$$$$$$$$$$$$$$$$$$$$$J%;)/'0$,K$L/0!"AL "0! O;)/'0I'0)1'--"1JJ?'()/05JJ?'()"6=!1%8$!'$+2%7+ $$3$===$')9"1$1'()"6$=== $$2%7=;'00";)$G:7%)9GF$J;'0)1'--"1$,K$L%77LF$ $$$$$$$$$$$$$$$$$$$$$$$J%;)/'0$,K$L/0!"AL $$3$===$')9"1$1'()"6$=== "0!

    in your plugin: in your app:
  25. O;)/'0I'0)1'--"1JJ?'()/05JJ?'()"6=!1%8$!'$+2%7+ $$2%7=;'00";)$G:7%)9GF$J;'0)1'--"1$,K$L7-(5/0LF$ $$$$$$$$$$$$$$$$$$$$$$$J%;)/'0$,K$L/0!"AL "0! O;)/'0I'0)1'--"1JJ?'()/05JJ?'()"6=!1%8$!'$+2%7+ $$3$===$')9"1$1'()"6$=== $$2%7=;'00";)$G:7%)9GF$J;'0)1'--"1$,K$L%77LF$ $$$$$$$$$$$$$$$$$$$$$$$J%;)/'0$,K$L/0!"AL $$3$===$')9"1$1'()"6$=== "0!

    in your plugin: in your app:
  26. Ticket #2592 (also Ticket #329)

  27. 785*$+,#-&$#)&785*$+,#-.!) 2'!(-"$P<H-(5/0 $$!"#$6"-#=%!!.1'()"6B7"*C $$$$2%7=;'00";)$L:6)(##LF$J;'0)1'--"1$,K$L)9/056L $$"0! "0! O;)/'0I'0)1'--"1JJ?'()/05JJ?'()"6=!1%8$!'$+2%7+ $$3$<'(1$%77$1'()"6=== $$P<H-(5/0=%!!.1'()"6B2%7C $$3$");===

    "0!
  28. what’s missing?

  29. public assets

  30. copy

  31. file clash

  32. 83+!5*$+,#-&#-%'"$$.!) 2<./2%5"6$,$H%)90%2"=0"8B@/-"=!/10%2"B..@QR4..CC$S$ $$$$$$$$$$$$$$L%66")6:/2%5"6L )%15")$,$?%/-6=1'')$S$L7(&-/;:/2%5"6:2<.7-(5/0L @/-"T)/-6=2U!/1.7B)%15")C 2<./2%5"6=;9/-!1"0="%;9$!'$+"+$ $$$$@/-"T)/-6=;7.1B"F$)%15")$S$"=&%6"0%2"C$ "0!

  33. 83+!5*$+,#-&#-%'"$$.!) 2<./2%5"6$,$H%)90%2"=0"8B@/-"=!/10%2"B..@QR4..CC$S$ $$$$$$$$$$$$$$L%66")6:/2%5"6L )%15")$,$?%/-6=1'')$S$L7(&-/;:/2%5"6:2<.7-(5/0L )%15")=2%U".6<2-/0UB2<./2%5"6C$(0-"66$)%15")="A/6)>

  34. migrations

  35. simple DSL

  36. rollback

  37. !&:2/51%)": $$VWWXWYWYYVYVZ[.%-79%=1& version 20090101121234 20090102142345 2008123123456 VWWXWYWVY[VZ[\.&")%=1& 7-(5/0:!&:2/51%)": $$VWW]YVZYZ[\^.5%22%=1&

  38. version 20090101121234 20090102142345 2008123123456 1%U"$!&J1'--&%;U P/51%)'1=1'--&%;U P/51%)'13;(11"0).D"16/'0 P/51%)'132/51%)"!=-%6) P/51%)'1=5").%--.D"16/'06 BL_4R4I`$D"16/'0$@?aP$

    $ $ $$6;9"2%.2/51%)/'06LC =2%7BbJ)'./C=6'1)
  39. it gets worse

  40. !&:2/51%)": $$WWY.%-79%=1& version 001 002 WWV.&")%=1& 7-(5/0:!&:2/51%)": $$WWY.5%22%=1&

  41. http://www.flickr.com/photos/bk2204/475332962/

  42. single timeline

  43. app migration 1 app migration 2 plugin migration 1 app

    migration 3 plugin migra install upgrade You Me
  44. app migration 1 app migration 2 plugin migration 1 app

    migration 3 plugin migration 2 You
  45. WW[.!"-)%=1& !&:2/51%)": $$WWY.%-79%=1& WWV.&")%=1& 7-(5/0:!&:2/51%)": $$WWY.5%22%=1& WWZ.7-(5/0.)'.WWY=1&

  46. WW[.!"-)%=1& !&:2/51%)": $$WWY.%-79%=1& WWV.&")%=1& 7-(5/0:!&:2/51%)": $$WWY.5%22%=1& WWZ.7-(5/0.)'.WWY=1& Copy & Retimestamp?

    Reference? Symlink?
  47. Ticket #2058 interblah.net/plugin-migrations

  48. my recommendation? (for the moment, at least)

  49. write a generator c$6;1/7):5"0"1%)"$%;)6.%6.#(.2/51%)/'06 $$$$ $$$"A/6)6$$!&:2/51%)" $$$;1"%)"$$!&:2/51%)":VWWXW\W\YYYZZd.&-%9=1& c$=== (within your

    plugin)
  50. techniques

  51. overriding functionality

  52. views just work

  53. controllers

  54. straight override

  55. None
  56. None
  57. module

  58. None
  59. None
  60. None
  61. namespaced

  62. None
  63. None
  64. None
  65. playing nice with the class cache

  66. 1/23*8/36/1**$#2"'#3-43-'!3$$(!/ 9"%/)((-/!(73:(;/6!37/'9(/73;+$(/ '!((/)+'/#%/%'#$$/"2'#:(<< < < < < < < !

  67. O;)/D"_(77'1)JJe"7"0!"0;/"6=-'%!.'0;".7%)96

  68. ApplicationController AppController PluginController

  69. ApplicationController PluginController

  70. 23-6#,&(-:#!3-7(-'.!) ?%/-6JJQ0/)/%-/f"1=1(0$!'$+;'0#/5+ $$3$");=== $$;'0#/5=1"-'%!.7-(5/06$,$)1(" $$ "0!

  71. 83+!5*$+,#-&"**&23-'!3$$(!%&,33;523-'!3$$(!.!) ;-%66$g''!I'0)1'--"1$h$=== $$(0-'%!%&-" $$ $$3$");$=== "0!

  72. init.rb woes

  73. ;'0#/5=)'.71"7%1"$!' $$ "0! 785*$+,#-&#-#'.!) $$_'2"O77I-%66="A)"0!BP<i"9%D/'(1C

  74. testing

  75. ApplicationController PluginController AppController

  76. ApplicationController PluginController Their Code Your Code

  77. None
  78. ! " # $

  79. None
  80. unit test?

  81. test in your own rails environment?

  82. plugin_test_helper

  83. I care about testing my chunk

  84. You care about testing your whole app

  85. empower the developer

  86. avoiding fail

  87. ;%6"$;'!"=;'06(2"1 $$89"0$;'!"=%()9'1 $$$$1"(6"=2'6)-<$,j$:"##";)/D": $$89"0$1%0!B!"D"-'7"1C $$$$1"(6"=)1/;U/"1.&().7'66/&-"B)1("C $$"-6" $$$$1"(6"='D"11%)"!N "0!

  88. consume wisely

  89. Serving Size 14 kloc Nutrition Facts Amount Per Serving 1

    bad engine Calories 10,666 Long Methods 1578g 34% God Objects 326g 7% Stress 320mg 119% Total Fat 2674g 98% Hairloss 45g 45.8% % Daily Value* Technical Debt 13g 87% Untested Code 1578mg 34% Hidden Bugs 326mg 7% Benefit 1mg 0.1%
  90. you will not be able to write some engines.

  91. you will not be able to use some engines.

  92. extract specific functionality

  93. establish some clear integration points

  94. you are customer #1

  95. READ the CODE

  96. james@lazyatom.com lets@gofreerange.com FIN