Best way to hook into class_attribute setter?

Rails
1

I have some class attributes that I’m setting in an
ActiveSupport::Concern
and would like to hook into class_attribute setters, but is really isn’t
acting like I would assume.

Here’s what I did to test. I didn’t create a different controller,
because
just wanted to try to do as little as possible to test this similarly to
how I’m doing in my gem in a clean environment.

rails new spike
created new .rvmrc in the spike dir so would autocreate its own gemset
and
use ruby 1.9.3 (using 1.9.3p194 (2012-04-20 revision 35410)
[x86_64-darwin11.4.0]).
cd spike
rm public/index.html
rails g controller home index
edit config/routes.rb to look like this:

Spike::Application.routes.draw do
get “home/index”
root :to => ‘home#index’
end

Added this to app/controllers/my_spike.rb:

module MySpike
extend ActiveSupport::Concern

included do
puts ‘included called’
class_attribute :foobar, instance_writer: true
end

module ClassMethods
def implement_some_methods(options = {})
puts ‘implement_some_methods called’
include SomeMethods
end

def foobar=(val)
  puts 'class method foobar= called'
  super
end

end

module SomeMethods

def foobar=(val)
  puts 'instance method foobar= called'
  super
end

def initialize
  puts 'initialize called'
  self.foobar = 'foo'
  puts "self.foobar=#{self.foobar}"
  self.class.foobar = 'bar'
  puts "self.class.foobar=#{self.class.foobar}"
end

def index
  puts 'index called'
end

end
end

And then put this into app/controllers/application_controller.rb:

class HomeController < ApplicationController
include MySpike
implement_some_methods

def index
end
end

So when I do:
rails s

and browse/curl to http://localhost:3000, I do not see either of my
attempts to be called in the console:

$ rails s
=> Booting WEBrick
=> Rails 3.2.8 application starting in development on
http://0.0.0.0:3000
=> Call with -d to detach
=> Ctrl-C to shutdown server
[2012-09-28 10:56:25] INFO WEBrick 1.3.1
[2012-09-28 10:56:25] INFO ruby 1.9.3 (2012-04-20)
[x86_64-darwin11.4.0]
[2012-09-28 10:56:25] INFO WEBrick::HTTPServer#start: pid=4732
port=3000
included called
implement_some_methods called
initialize called
self.foobar=foo
self.class.foobar=bar

Started GET “/” for 127.0.0.1 at 2012-09-28 10:56:30 -0400
Connecting to database specified by database.yml
Processing by HomeController#index as HTML
Rendered home/index.html.erb (1.6ms)
Completed 200 OK in 8ms (Views: 7.9ms | ActiveRecord: 0.0ms)
[2012-09-28 10:56:30] WARN Could not determine content-length of
response
body. Set content-length of the response or set Response#chunked = true

Thanks in advance!

2

This definitely is at least partially because of the order of execution
in
ActiveSupport::Concern:

    base.extend const_get("ClassMethods") if

const_defined?(“ClassMethods”)
if const_defined?(“InstanceMethods”)
base.send :include, const_get(“InstanceMethods”)
ActiveSupport::Deprecation.warn “The InstanceMethods module
inside ActiveSupport::Concern will be "
“no longer included automatically. Please define instance
methods directly in #{self} instead.”, caller
end
base.class_eval(&@_included_block) if
instance_variable_defined?(”@_included_block")

But, the following doesn’t use the foobar setter overrides, probably
because I have the wrong scope for the include and extend that I’ve now
added in the included block:

module MySpike
extend ActiveSupport::Concern

included do
puts ‘included called’
class_attribute :foobar, instance_writer: true
extend ClassMethodsAfterIncluded
include InstanceMethodsAfterIncluded
end

module ClassMethodsAfterIncluded
def foobar=(val)
puts ‘class method foobar= called’
super
end
end

module InstanceMethodsAfterIncluded
def foobar=(val)
puts ‘instance method foobar= called’
super
end
end

module ClassMethods
def implement_some_methods(options = {})
puts ‘implement_some_methods called’
include SomeMethods
end
end

module SomeMethods
# note: copied from comments below
def initialize
puts ‘initialize called’
self.foobar = ‘foo’
puts “self.foobar=#{self.foobar}”
self.class.foobar = ‘bar’
puts “self.class.foobar=#{self.class.foobar}”
end

def index
  puts 'index called'
end

end

end