Per-Instance Callbacks

This patch allows callbacks to be hooked up on an individual instance.

class SomeStorage
  include ActiveSupport::Callbacks
  define_callbacks :before_save, :after_save
  def save
    run_callbacks(:before_save)
    puts "- save"
    run_callbacks(:after_save)
  end
end

store = SomeStorage.new

store.before_save do |object|
  puts "saving..."
end

store.after_save do |object|
  puts "saved."
end

store.save

#
# Output:
#   saving...
#   - save
#   saved