[code language=”ruby”]
1. views

class ApplicationController < ActionController::Base
helper :all# include all helpers
end

2. Controller methods in views

class ApplicationController < ActionController::Base

helper_method :current_store

#now controller_method can be accessed in views

end

2. Helper methods in controller

class ApplicationController < ActionController::Base

include ActionView::Helpers::ApplicationHelper

end

3. Helper methods in model

class Teacher < ActiveRecord::Base

include ActionView::Helpers::ApplicationHelper

end

4. Helper methods in mailer

class Student < ActionMailer::Base

add_template_helper(ApplicationHelper)

end
[/code]