naming.rb

require 'active_support/inflector'

module ActiveModel
  class Name < String
    attr_reader :singular, :plural, :element, :collection, :partial_path
    alias_method :cache_key, :collection

    def initialize(klass)
      super(klass.name)
      @klass = klass
      @singular = ActiveSupport::Inflector.underscore(self).tr('/', '_').freeze
      @plural = ActiveSupport::Inflector.pluralize(@singular).freeze
      @element = ActiveSupport::Inflector.underscore(ActiveSupport::Inflector.demodulize(self)).freeze
      @human = ActiveSupport::Inflector.humanize(@element).freeze
      @collection = ActiveSupport::Inflector.tableize(self).freeze
      @partial_path = "#{@collection}/#{@element}".freeze
    end

    # Transform the model name into a more humane format, using I18n. By default,
    # it will underscore then humanize the class name (BlogPost.model_name.human #=> "Blog post").
    # Specify +options+ with additional translating options.
    def human(options={})
      return @human unless @klass.respond_to?(:lookup_ancestors) &&
                           @klass.respond_to?(:i18n_scope)

      defaults = @klass.lookup_ancestors.map do |klass|
        klass.model_name.underscore.to_sym
      end

      defaults << options.delete(:default) if options[:default]
      defaults << @human

      options.reverse_merge! :scope => [@klass.i18n_scope, :models], :count => 1, :default => defaults
      I18n.translate(defaults.shift, options)
    end
  end

  module Naming
    # Returns an ActiveModel::Name object for module. It can be
    # used to retrieve all kinds of naming-related information.
    def model_name
      @_model_name ||= ActiveModel::Name.new(self)
    end
  end
end