Set particular locales for application (kslazarev#135)

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ### Features
   * Your contribution here.
+  * Set particular locales for application. \[[#135](https://github.com/kslazarev/numbers_and_words/issues/135)\] \([@seniorihor](https://github.com/seniorihor)\) \(assignee: [@seniorihor](https://github.com/seniorihor)\)
+
   * Add option `precision` to `to_words`. \[[#134](https://github.com/kslazarev/numbers_and_words/issues/134)\] \([@neodelf](https://github.com/neodelf)\) \(assignee: [@neodelf](https://github.com/neodelf)\)
 
 ### Bugs

README.rdoc

@@ -250,6 +250,23 @@ I18n kütüphanesi ile sayıları yazıya çevirir.
     I18n.with_locale(:ru) { 0.1.to_words precision: 3 }
     => ноль целых и десять сотых
 
+== Locales configuration / Конфигурация локалей
+
+You may optionally set locales you want to work with in your application.
+
+First, add to your Gemfile ("require: false" needed for config to take effect)
+
+  gem 'numbers_and_words', require: false
+
+Then create your configuration in config/initializers/numbers_and_words.rb
+
+  module NumbersAndWords
+    module I18n
+      APP_LOCALES = ["en", "ru"]
+    end
+  end
+  require "numbers_and_words"
+
 == Requirements / Требования / Configuration Requise
 
 * 1.9.3 <= Ruby (compatible with/совместимость с/compatible avec Ruby 1.9, JRuby and/и/et Rubinius);

lib/numbers_and_words/i18n/initialization.rb

@@ -4,9 +4,22 @@ module Initialization
       extend self
 
       def init
-        I18n.locale_files.each { |locale_file| ::I18n.load_path << locale_file}
+        I18n.locale_files.each { |locale_file| ::I18n.load_path << locale_file if app_locale?(locale_file) }
         NumbersAndWords::I18n::Pluralization.init
       end
+
+      private
+
+      def app_locale?(file)
+        return true unless app_locales
+
+        locale = file.split('.')[-2]
+        app_locales.include?(locale)
+      end
+
+      def app_locales
+        @app_locales ||= (I18n::APP_LOCALES if I18n.const_defined?(:APP_LOCALES))
+      end
     end
   end
 end