Seperation of concerns without meta-madness and namespace pollution.

Normal includes and extensions pollute the namespace and share private/protected.
With concern, everything stays in the Concern, can access the concerned and keep namespaced+private.

Install

As Gem: sudo gem install grosser-concern -s http://gems.github.com
Or as Rails plugin: script/plugins install git://github.com/grosser/concern.git

Usage

Normal usage: # a.rb require 'concern' class A concern 'a/acl'

  def admin? ...
end

# a/acl.rb
class A::ACL < Concern
  def can_access?(vault)
    admin? and secret
  end

  private

  def secrect ...
end

A.new.acl.can_access?(BankAccount)

Delegate usage:

class A
  class Message
    def write_message ...
    def read_message ...
  end

  concern 'a/acl', :delegate => :true # all public
  concern 'a/messages', :delegate => [:write_message]
end

A.new.can_access?(BankAccount)
A.new.write_message
A.new.message.read_message

Adding to concerned: class A class B < Concern def initialize super @something = {} end

    def self.included(base)
      base.class_eval do
        test
      end
    end
  end

  def self.test
    puts "it works"
  end

  concern 'a/b'
end

More examples can be found in spec/examples

Author

Michael Grosser
grosser.michael@gmail.com
Hereby placed under public domain, do what you want, just do not hold me accountable...