The Even Darker Art Of Rails Engines 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!

appable_plugins

desert

merb slices?

engines

!quot;#$%&!quot;#$'#(%&$#)&!quot;#$%&*$+,#-.!) !quot;#$%&'() $$*%&'()$++,$-'%!.%&'()./0#'12%)/'0 quot;0! 3$405/0quot;6$%1quot;$7-(5/06$8/)9$%0$%77:$!/1quot;;)'1<= !quot;#$quot;05/0quot;> $$9%6.%77.!/1quot;;)'1<> quot;0! 3$?quot;)(106$)1(quot;$/#$)9quot;$quot;05/0quot;$69/76$8/)9$%$1'()/05$#/-quot; !quot;#$1'()quot;!> $$@/-quot;=quot;A/6)>B1'()/05.#/-quot;C quot;0! !quot;#$D/quot;8.7%)9 $$@/-quot;=E'/0B!/1quot;;)'1<F$G%77GF$GD/quot;86GC quot;0!

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

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

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

Ticket #1905

conﬁg/routes.rb

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

top precedence

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

Ticket #2592 (also Ticket #329)

785*$+,#-&$#)&785*$+,#-.!) 2'!(-quot;$P<H-(5/0 $$!quot;#$6quot;-#=%!!.1'()quot;6B7quot;*C $$$$2%7=;'00quot;;)$L:6)(##LF$J;'0)1'--quot;1$,K$L)9/056L $$quot;0! quot;0! O;)/'0I'0)1'--quot;1JJ?'()/05JJ?'()quot;6=!1%8$!'$+2%7+ $$3$<'(1$%77$1'()quot;6=== $$P<H-(5/0=%!!.1'()quot;6B2%7C $$3$quot;);=== quot;0!

what’s missing?

public assets

ﬁle clash

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

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

migrations

simple DSL

rollback

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

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

it gets worse

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

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

single timeline

You 1 n tio n1 ra tio ig gra m pp mi a n2 in ug tio l p gra 3 i ion m Me at pp igr a all pm ra nst p ig a i nm gi plu de ra pg u

n1 tio You gra n1 i tio m gra pp mi a n2 gin tio plu ra n3 ig pm tio ra ap n2 ig tio pm gra ap mi gin plu

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

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

Ticket #2058 interblah.net/plugin-migrations

my recommendation? (for the moment, at least)

write a generator (within your plugin) c$6;1/7):5quot;0quot;1%)quot;$%;)6.%6.#(.2/51%)/'06 $$$$ $$$quot;A/6)6$$!&:2/51%)quot; $$$;1quot;%)quot;$$!&:2/51%)quot;:VWWXWWYYYZZd.&-%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**$#2quot;'#3-43-'!3$$(!/ ! 9quot;%/)((-/!(73:(;/6!37/'9(/73;+$(/ < < '!((/)+'/#%/%'#$$/quot;2'#:(<< < < <<

O;)/Dquot;_(77'1)JJequot;7quot;0!quot;0;/quot;6=-'%!.'0;quot;.7%)96

ApplicationController AppController PluginController

ApplicationController PluginController

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

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

init.rb woes

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

testing

ApplicationController AppController PluginController

ApplicationController ode ir C The Code Your PluginController

quot; $ ! #

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

;%6quot;$;'!quot;=;'06(2quot;1 $$89quot;0$;'!quot;=%()9'1 $$$$1quot;(6quot;=2'6)-<$,j$:quot;##quot;;)/Dquot;: $$89quot;0$1%0!B!quot;Dquot;-'7quot;1C $$$$1quot;(6quot;=)1/;U/quot;1.&().7'66/&-quot;B)1(quot;C $$quot;-6quot; $$$$1quot;(6quot;='Dquot;11%)quot;!N quot;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% Untested Code 1578mg 34% 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

The Even Darker Art Of Rails Engines Presentation

by railsconf on May 06, 2009

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The Even Darker Art Of Rails Engines Presentation — Presentation Transcript