module ActionController::Helpers::ClassMethods

def all_application_helpers

Extract helper names from files in app/helpers/**/*_helper.rb 
def all_application_helpers
  all_helpers_from_path(helpers_path)
end

def all_helpers_from_path(path)

# => ["application", "chart", "rubygems"]
ActionController::Base.all_helpers_from_path 'app/helpers'

Returns a list of helper names in a given path. 
def all_helpers_from_path(path)
  helpers = Array(path).flat_map do |_path|
    names = Dir["#{_path}/**/*_helper.rb"].map { |file| file[_path.to_s.size + 1..-"_helper.rb".size - 1] }
    names.sort!
  end
  helpers.uniq!
  helpers
end

def helper_attr(*attrs)

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

helper_attr :name
attr_accessor :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

instead when using +capture+.
using {helper}[rdoc-ref:AbstractController::Helpers::ClassMethods#helper]
This may cause incorrect behaviour with capture methods. Consider
Note that the proxy is rendered under a different view context.

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

def modules_for_helpers(args)

* array - A normalized list of modules for the list of helpers provided.
==== Returns

* args - A list of helpers
==== Parameters

all helpers in helpers_path.
Override 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