Even-Darker Art of Rails Engines @lazyatom - PowerPoint PPT Presentation

The Even-Darker Art of Rails Engines

@lazyatom

github.com/lazyatom/engines

Rails 2.3

history

November 2005

it’s distracting!

reuse is overrated!

Evil! Evil! Evil! Evil! Evil! Evil! Evil! Evil! Shit!

eek!

appable_plugins

desert

merb slices?

engines

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

app/controllers/ models/ helpers/ views/ metal/

*$+,#-&"**&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!

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

Ticket #1905

config/routes.rb

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

top precedence

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

Ticket #2592 (also Ticket #329)

785*$+,#-&$#)&785*$+,#-.!) 2'!(-"$P<H-(5/0 $$!"#$6"-#=%!!.1'()"6B 7"* C $$$$2%7=;'00";)$L:6)(##LF$J;'0)1'--"1$,K$L)9/056L $$"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!

what’s missing?

public assets

copy

file clash

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!

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)>

migrations

simple DSL

rollback

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

1%U"$!&J1'--&%;U version P/51%)'1=1'--&%;U 20090101121234 P/51%)'13;(11"0).D"16/'0 20090102142345 P/51%)'132/51%)"!=-%6) 2008123123456 P/51%)'1=5").%--.D"16/'06 BL_4R4I`$D"16/'0$@?aP$ $ $ $$6;9"2%.2/51%)/'06LC =2%7BbJ)'./C=6'1)

it gets worse

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

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

single timeline

You app migration 1 plugin migration 1 app migration 2 app migration 3 Me plugin migration 2 install upgrade

app migration 1 plugin migration 1 You app migration 2 app migration 3 plugin migration 2

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

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

Ticket #2058 interblah.net/plugin-migrations

my recommendation? (for the moment, at least)

write a generator (within your plugin) 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$===

techniques

overriding functionality

views just work

controllers

straight override

module

namespaced

playing nice with the class cache

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

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

ApplicationController AppController PluginController

ApplicationController PluginController

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

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

init.rb woes

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

testing

ApplicationController AppController PluginController

ApplicationController Their Code Your Code PluginController

� � � �

unit test?

test in your own rails environment?

plugin_test_helper

I care about testing my chunk

You care about testing your whole app

empower the developer

avoiding fail

;%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!

consume wisely

Nutrition Facts Serving Size 14 kloc Amount Per Serving 1 bad engine Calories 10,666 % Daily Value* Total Fat 2674g 98 % 34 % Long Methods 1578g 7 % God Objects 326g Stress 320mg 119 % Hairloss 45g 45.8 % Technical Debt 13g 87 % 34 % Untested Code 1578mg 7 % Hidden Bugs 326mg Benefit 1mg 0.1 %

you will not be able to write some engines.

you will not be able to use some engines.

extract specific functionality

establish some clear integration points

you are customer #1

READ the CODE

james@lazyatom.com FIN lets@gofreerange.com