Upgrade to Pro
— share decks privately, control downloads, hide ads and more …
Speaker Deck
Features
Speaker Deck
PRO
Sign in
Sign up for free
Search
Search
What the hell is ActiveSupport::Concern?
Search
Aaron Patterson
December 04, 2012
Programming
5
270
What the hell is ActiveSupport::Concern?
A short talk about ActiveSupport::Concern.
Aaron Patterson
December 04, 2012
Tweet
Share
More Decks by Aaron Patterson
See All by Aaron Patterson
Speeding up Instance Variables in Ruby 3.3
tenderlove
2
350
[Feature #20425] Speeding up delegate methods
tenderlove
3
220
RailsConf 2023
tenderlove
29
1k
Don't @ Me! Faster Instance Variables with Object Shapes
tenderlove
1
420
RailsConf 2022 Keynote
tenderlove
2
510
Some Assembly Required
tenderlove
1
520
HexDevs 2021
tenderlove
1
400
Compacting GC for MRI
tenderlove
60
4.5k
But At What Cost?
tenderlove
9
14k
Other Decks in Programming
See All in Programming
Ruby on cygwin 2025-02
fd0
0
140
時計仕掛けのCompose
mkeeda
1
290
GAEログのコスト削減
mot_techtalk
0
120
Boost Performance and Developer Productivity with Jakarta EE 11
ivargrimstad
0
220
Linux && Docker 研修/Linux && Docker training
forrep
24
4.5k
SpringBoot3.4の構造化ログ #kanjava
irof
2
990
color-scheme: light dark; を完全に理解する
uhyo
3
250
Conform を推す - Advocating for Conform
mizoguchicoji
3
690
チームリードになって変わったこと
isaka1022
0
200
CloudNativePGがCNCF Sandboxプロジェクトになったぞ! 〜CloudNativePGの仕組みの紹介〜
nnaka2992
0
230
WebDriver BiDiとは何なのか
yotahada3
1
140
SRE、開発、QAが協業して挑んだリリースプロセス改革@SRE Kaigi 2025
nealle
3
4.3k
Featured
See All Featured
XXLCSS - How to scale CSS and keep your sanity
sugarenia
248
1.3M
Let's Do A Bunch of Simple Stuff to Make Websites Faster
chriscoyier
507
140k
How To Stay Up To Date on Web Technology
chriscoyier
790
250k
Building Flexible Design Systems
yeseniaperezcruz
328
38k
Product Roadmaps are Hard
iamctodd
PRO
50
11k
Site-Speed That Sticks
csswizardry
4
380
Practical Tips for Bootstrapping Information Extraction Pipelines
honnibal
PRO
12
960
The Success of Rails: Ensuring Growth for the Next 100 Years
eileencodes
44
7k
CSS Pre-Processors: Stylus, Less & Sass
bermonpainter
356
29k
Build your cross-platform service in a week with App Engine
jlugia
229
18k
Embracing the Ebb and Flow
colly
84
4.6k
The Invisible Side of Design
smashingmag
299
50k
Transcript
Thanks!
Hark
Substantial
What the hell is ActiveSupport::Concern?
I have no idea.
U Concerned, Bro?
Aaron Patterson @tenderlove
Lead Pun Architect
Substantial, Thanks
None
Gorbachev Puff-Puff Thunderhorse
None
None
None
None
None
None
Rails Core ~ 3 years (I think)
Confession
What’s in a name?
Classes ❤ File ❤ Hash ❤ Set ❤ Array
Modules ❤ Enumerable ❤ Comparable
AS::Concern
“Concern” is a noun
“Concern” is a noun
“Son, We’re Concerned”
Grown Man.
Stay Classy Change Your Self Track Dependents
Stay Classy.
Class Methods module MyEnumerable def my_first end module ClassMethods def
my_new end end def self.included(klass) klass.extend ClassMethods end end
Including class Aaron include MyEnumerable end p Aaron.respond_to?(:my_new) # =>
true p Aaron.new.respond_to?(:my_first) # => true
With Concern module MyEnumerable extend ActiveSupport::Concern def my_first end module
ClassMethods def my_new end end end
Including class Aaron include MyEnumerable end p Aaron.respond_to?(:my_new) # =>
true p Aaron.new.respond_to?(:my_first) # => true
Be Careful!
Normal Include module MyEnumerable def my_first end end class Aaron
p singleton_methods # => [] include MyEnumerable p singleton_methods # => [] end
Normal Extend module MyEnumerable def my_first end end class Aaron
p singleton_methods # => [] extend MyEnumerable p singleton_methods # => [:my_first] end
Users May Be Surprised
Do I need this?
Are you coupled?
Change Your Self.
Setting up ivars
Class Accessor module MyEnumerable module ClassMethods attr_accessor :foo end def
self.included klass klass.extend ClassMethods end end
Warning! class Aaron include MyEnumerable p foo end
Warning! class Aaron include MyEnumerable p foo end @foo not
initialized
Class Accessor module MyEnumerable module ClassMethods attr_accessor :foo end def
self.included klass klass.extend ClassMethods @foo = 10 end end
Class Accessor module MyEnumerable module ClassMethods attr_accessor :foo end def
self.included klass klass.extend ClassMethods @foo = 10 end end self == MyEnumerable
Class Accessor module MyEnumerable module ClassMethods attr_accessor :foo end def
self.included klass klass.extend ClassMethods klass.class_eval do @foo = 10 end end end
Working Code class Aaron include MyEnumerable p foo # =>
10 end
With Concern module MyEnumerable extend ActiveSupport::Concern module ClassMethods attr_accessor :foo
end included do @foo = 10 end end self == included class
Isolating Setup
Class Method Calls class Foo < ActiveRecord::Base scope :foo, ->
{ ... } scope :bar, -> { ... } scope :baz, -> { ... } # other methods end
Module Extraction module Findable def self.included(klass) klass.scope :foo, -> {
... } klass.scope :bar, -> { ... } klass.scope :baz, -> { ... } end end
Module Extraction module Findable def self.included(klass) klass.scope :foo, -> {
... } klass.scope :bar, -> { ... } klass.scope :baz, -> { ... } end end
class_eval module Findable def self.included(klass) klass.class_eval do scope :foo, ->
{ ... } scope :bar, -> { ... } scope :baz, -> { ... } end end end
Concerned module Findable extend ActiveSupport::Concern included do scope :foo, ->
{ ... } scope :bar, -> { ... } scope :baz, -> { ... } end end
Track Your Dependents.
Two Modules module Foo module ClassMethods def some_method end #
.... end end module Bar def self.included klass klass.some_method end end
Bar depends on Foo
Usage class Aaron include Foo include Bar end
Usage - BOOM! class Aaron include Bar include Foo end
Try to Fix module Foo module ClassMethods def some_method end
end end module Bar include Foo def self.included klass klass.some_method end end
Try to Fix module Foo module ClassMethods def some_method end
end end module Bar include Foo def self.included klass klass.some_method end end
Fix with class_eval module Bar def self.included klass klass.class_eval do
include Foo end klass.some_method end end
Concerned module Bar extend ActiveSupport::Concern include Foo included do some_method
end end
Concerned module Bar extend ActiveSupport::Concern include Foo included do some_method
end end NOT Ruby’s Include
When should I be concerned?
You probably shouldn’t be.
Can you simplify?
Many Dependencies
THANKS!