module ActionController::Helpers::ClassMethods

def all_application_helpers

Extract helper names from files in app/helpers/**/*_helper.rb 
def all_application_helpers
  helpers = []
  Array.wrap(helpers_path).each do |path|
    extract  = /^#{Regexp.quote(path.to_s)}\/?(.*)_helper.rb$/
    helpers += Dir["#{path}/**/*_helper.rb"].map { |file| file.sub(extract, '\1') }
  end
  helpers.sort!
  helpers.uniq!
  helpers
end

def helper_attr(*attrs)

into helpers.
*attrs:: Names of attributes to be converted
==== Parameters

attr_accessor :name
helper_attr :name
controller and makes them available to the view:
following adds new +name+ and name= instance methods to a
Declares helper accessors for controller attributes. For example, the 
def helper_attr(*attrs)
  attrs.flatten.each { |attr| helper_method(attr, "#{attr}=") }
end

def helpers

Provides a proxy to access helpers methods from outside the view. 
def helpers
  @helper_proxy ||= ActionView::Base.new.extend(_helpers)
end

def helpers_dir 

def helpers_dir
  ActiveSupport::Deprecation.warn "helpers_dir is deprecated, use helpers_path instead", caller
  self.helpers_path
end

def helpers_dir=(value) 

def helpers_dir=(value)
  ActiveSupport::Deprecation.warn "helpers_dir= is deprecated, use helpers_path= instead", caller
  self.helpers_path = Array.wrap(value)
end

def modules_for_helpers(args)

helpers provided.
Array[Module]:: A normalized list of modules for the list of
==== Returns

args:: A list of helpers
==== Parameters

all helpers in helpers_dir.
Overwrite modules_for_helpers to accept :all as argument, which loads 
def modules_for_helpers(args)
  args += all_application_helpers if args.delete(:all)
  super(args)
end