avoiding included {} with ActiveSupport::Concern

gistfile1.md

We can call a class macro on an instance of a class like this:

class Foo attr_accessor :bar end

Foo.new.bar = 1

We can call a class macro on the class in this way:

class Person class << self attr_accessor :name end end

Person.name = "Luke"

Let's say we want to have this happen automatically when we include a module. In the following example, as klass is equal to self in the declaration above "class << self", we can apply the same technique we used above.

module Age def self.included(klass) class << klass attr_accessor :age end end end

If we'd included that module in to Person, we could then do:

Person.age = "old enough to know better"