Ruby on Rails i18n revisited

Having a requirement for both internationalization and per-instance customizability of translations in our soon to be revealed application, I wanted to go with an as-simple-as-possible pure Ruby solution for translating strings.

While gettext based approaches might have some advantages over this (some tools available, possibly faster speed with C-based variants) I didn’t want to go with a sledgehammerized solution (I’ve very few strings in the app, and I really only need to support a handful of languages), so I’ve come up with this:

# .rb files to define l10ns in (lang/ and lang/custom/)
Localization.define('de_DE') do |l|
  l.store "blah", "blub"
  l.store "testing %d", ["Singular: %d", "Plural: %d"]
end

# Call from anywhere (extension to Object class):
_('blah')
_('testing %d', 5)

# in .rhtml
<%=_ 'testing %d', 1 %>

# current language is a class var in class
# Localization, so set e.g. in application.rb
Localization.lang = 'de_DE'

# in environment.rb (rails 0.13.1)
Localization.load

All you need to include for this is the following localization.rb file, which you stick in your lib directory:

module Localization
  mattr_accessor :lang

  @@l10s = { :default => {} }
  @@lang = :default

  def self._(string_to_localize, *args)
    translated =
      @@l10s[@@lang][string_to_localize] || string_to_localize
    return translated.call(*args).to_s if translated.is_a? Proc
    translated =
      translated[args[0]>1 ? 1 : 0] if translated.is_a?(Array)
    sprintf translated, *args
  end

  def self.define(lang = :default)
    @@l10s[lang] ||= {}
    yield @@l10s[lang]
  end

  def self.load
    Dir.glob("#{RAILS_ROOT}/lang/*.rb"){ |t| require t }
    Dir.glob("#{RAILS_ROOT}/lang/custom/*.rb"){ |t| require t }
  end

end

class Object
  def _(*args); Localization._(*args); end
end

It should be easy to alter or extend that for your own purposes, or just use it as-is.

Update: Changed to module; and here’s a very quick hack to extract a nice pre-generated guesstimation of a l10n file:

# Generates a best-estimate l10n file from all views by
# collecting calls to _() -- note: use the generated file only
# as a start (this method is only guesstimating)
def self.generate_l10n_file
  "Localization.define('en_US') do |l|n" <<
  Dir.glob("#{RAILS_ROOT}/app/views/**/*.rhtml").collect do |f|
    ["# #{f}"] << File.read(f).scan(/<%.*[^w]_s*["'](.*?)["']/)
  end.uniq.flatten.collect do |g|
    g.starts_with?('#') ? "n  #{g}" : "  l.store '#{g}', '#{g}'"
  end.uniq.join("n") << "nend"
end

To use that, call up script/console and do a puts Localization.generate_l10n_file.

Update 2: I’ve added support for using nice lambda blocks of code for those “speciality” translations. The block gets passed the *args given to the _ method, so you can basically do anything:

Localization.define do |l|
   l.store '(time)', lambda { |t| t.strftime('%I:%M%p') }
end

Localization.define('de_DE') do |l|
   l.store '(time)', lambda { |t| t.strftime('%H:%M') }
end

_ '(time)', Time.now =>"10:13PM"
Localization.lang = 'de_DE'
_ '(time)', Time.now => "22:13"