The Even Darker Art of Rails Engines

Transcript

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