The Even Darker Art of Rails Engines

Given at RailsConf 2009

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?
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"%)"$$!&:2/51%)":VWWXW\W\YYYZZd.&-%9=1& c$=== (within your plugin)
50. techniques
51. overriding functionality
52. views just work
53. controllers
54. straight override
57. module
61. namespaced
65. playing nice with the class cache
66. 1/23*8/36/1**$#2"'#3-43-'!3$$(!/ 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*$+,#-&#-#'.!) $$_'2"O77I-%66="A)"0!BP<i"9%D/'(1C
74. testing
75. ApplicationController PluginController AppController
76. ApplicationController PluginController Their Code Your Code
78. ! " # $
80. unit test?
81. test in your own rails environment?
82. plugin_test_helper
83. I care about testing my chunk
84. You care about testing your whole app
85. empower the developer
86. avoiding fail
87. ;%6"$;'!"=;'06(2"1 $$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