The Even-Darker Art of Rails Engines
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The
Even-Darker Artof
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$J%--won’t load from your plugin
Ticket #1905
config/routes.rb
O;)/'0I'0)1'--"1JJ?'()/05JJ?'()"6=!1%8$!'$+2%7+
$$2%7=;'00";)$G:7%)9GF$J;'0)1'--"1$,K$L7-(5/0LF$$$$$$$$$$$$$$$$$$$$$$$$J%;)/'0$,K$L/0!"AL
"0!
*$+,#-&23-6#,&!3+'(%.!)
top precedence
O;)/'0I'0)1'--"1JJ?'()/05JJ?'()"6=!1%8$!'$+2%7+$$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:
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:
Ticket #2592(also Ticket #329)
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
$$3$");==="0!
what’s missing?
public assets
copy
file clash
83+!5*$+,#-&#-%'"$$.!)
2<./2%5"6$,$H%)90%2"=0"8B@/-"=!/10%2"[email protected]$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"[email protected]$S$$$$$$$$$$$$$$$L%66")6:/2%5"6L)%15")$,$?%/-6=1'')$S$L7(&-/;:/2%5"6:2<.7-(5/0L
)%15")=2%U".6<2-/0UB2<./2%5"6C$(0-"66$)%15")="A/6)>
migrations
simple DSL
rollback
!&:2/51%)":$$VWWXWYWYYVYVZ[.%-79%=1&
version
20090101121234
20090102142345
2008123123456
VWWXWYWVY[VZ[\.&")%=1&
7-(5/0:!&:2/51%)":$$VWW]YVZYZ[\^.5%22%=1&
version
20090101121234
20090102142345
2008123123456
1%U"$!&J1'--&%;U
P/51%)'1=1'--&%;U
P/51%)'13;(11"0).D"16/'0
P/51%)'132/51%)"!=-%6)
P/51%)'1=5").%--.D"16/'06
BL_4R4I`$D"16/'0$@?aP$$$$$6;9"2%.2/51%)/'06LC=2%7BbJ)'./C=6'1)
it gets worse
!&:2/51%)":$$WWY.%-79%=1&
version
001
002
WWV.&")%=1&
7-(5/0:!&:2/51%)":$$WWY.5%22%=1&
http://www.flickr.com/photos/bk2204/475332962/
single timeline
app migration 1
app migration 2
plugin migration 1
app migration 3
plugin migration 2
install
upgrade
You
Me
app migration 1
app migration 2
plugin migration 1
app migration 3
plugin migration 2
You
WW[.!"-)%=1&
!&:2/51%)":$$WWY.%-79%=1&
WWV.&")%=1&
7-(5/0:!&:2/51%)":$$WWY.5%22%=1&
WWZ.7-(5/0.)'.WWY=1&
WW[.!"-)%=1&
!&:2/51%)":$$WWY.%-79%=1&
WWV.&")%=1&
7-(5/0:!&:2/51%)":$$WWY.5%22%=1&
WWZ.7-(5/0.)'.WWY=1&
Copy & Retimestamp?
Reference?
Symlink?
Ticket #2058interblah.net/plugin-migrations
my recommendation?(for the moment, at least)
write a generator
c$6;1/7):5"0"1%)"$%;)6.%6.#(.2/51%)/'06$$$$$$$"A/6)6$$!&:2/51%)"$$$;1"%)"$$!&:2/51%)":VWWXW\W\YYYZZd.&-%9=1&
c$===
(within your plugin)
techniques
overriding functionality
views just work
controllers
straight override
module
namespaced
playing nice with the class cache
1/23*8/36/1**$#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-'%!%&-"$$$$3$");$===
"0!
init.rb woes
;'0#/5=)'.71"7%1"$!'
$$"0!
785*$+,#-&#-#'.!)
$$_'2"O77I-%66="A)"0!BP<i"9%D/'(1C
testing
ApplicationController
PluginControllerAppController
ApplicationController
PluginController
Their Code
Your Code
!"
#$
unit test?
test in your own rails environment?
plugin_test_helper
I care about testing my chunk
You care about testing your whole app
empower the developer
avoiding fail
;%6"$;'!"=;'06(2"1
$$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
Serving Size 14 klocNutrition 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%
you will not be able to write some engines.
you will not be able to use some engines.
extractspecific functionality
establish someclear integration points
you are customer #1
READ the CODE
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