I18n feature in Rails2.2
Overview of recent Rails support for localization

Who am I?
• Renaud Morvan (http://twitter.com/neleanth)
• 3 years of professional Rails Dev at http://
feedback20.com
• App localized in 6 languages
• Used Ruby-Gettext-Package then switched
to custom implementation

Some History
• No built-in support for I18n before Rails 2.2
• Tons of plugin available: http://
wiki.rubyonrails.org/rails/pages/
internationalizationcomparison
• Lots of monkey patching needed => huge
risk of breakage

late ‘07: Turning Point
• Sep ‘07: Change in Rails patch policy
delegating more power to the community
• Major I18n plugin dev regroup around a
common patch: Get rid of monkey patch +
common API
• Then lots of debate and no consensus
• Early ‘08: patch stalled

Eventually...
• Jul ’07 Sven Fuchs (Globalize plugin dev) get
back to work, rewrite the patch
• Rails edge is patched and I18n gem is
bundled with it.
• Released in Rails2.2

What is I18n Gem?
• A Common Api:
module I18n
# Sets the current locale pseudo-globally (threadsafe)
def locale=(locale); end
# Translates, pluralizes and interpolates a given key
def translate(key, options = {}); end
alias :t :translate
# Localizes time, dates and numbers to local formatting.
def localize(object, options = {}); end
alias :l :localize
...
end

What is I18n Gem?
• A backend implementing it (you can use
your own)
class I18n::Backend:: Simple
def load_translations(*filenames); end
def store_translations(locale, data); end
def translate(locale, key, options = {}); end
def localize(locale, object, format = :default); end
end

I18n.t basics 1/2
• Key: I18n.t 'date.formats.short'
I18n.t :'date.formats.short'
• Scope: I18n.t 'date.formats.short'
I18n.t 'formats.short', :scope => 'date'
I18n.t 'short', :scope => 'date.formats'
I18n.t 'short', :scope => ['date','formats']
• Pluralization: I18n.t :foo, :count => 0 # => 'Foos'
I18n.t :foo, :count => 1 # => 'Foo'
I18n.t :foo, :count => 2 # => 'Foos'
• Interpolation: given :foo => \"foo {{bar}}\"
I18n.t :foo, :bar => 'toto' # => 'foo toto'

I18n.t Basics 2/2
• Missing translation:
I18n.t :missing # raise I18n::MissingTranslationData
• Default (can be translation if :sym):
I18n.t :missing, :default => 'default' # => 'default'
• Bulk:
I18n.t :missing, :default => [:missing_too, 'default']
I18n.t [:'baz.foo', :'baz.bar']
• AllinOne:
I18n.t ['attr1.blank', :'attr2.blank'], :count => 2,
:scope => [:activerecord, :attributes], :default =>
[:'model.blank'], :attribute_name => 'attr1'# yuk !

I18n.l
• Time, TimeZone, DateTime
I18n.l Time.zone.now, :format => 'long'
# => \"dimanche 30 novembre 2008 11:29:49 UTC\"
• Date
I18n.l Date.today, :format => 'long'
# => \"30 novembre 2008\"

I18n API
• Simple and efficient for I18n in model code
• Minimal impact on Rails core code
• Provide I18n for any Rails plugin !
• Not that simple to implement backend:
those features are MANDATORY for rails
• One method to Translate them all! =>
difficult to parse, optimize

I18n::SimpleBackend
• Implement the API and the features
• Storage YML (nested hash) or ruby
• Yet a bit slow:
Benchmark.realtime { 10000.times do
I18n.t [:date, :format, :short]; end; }
# => 1.50350284576416
Benchmark.realtime {10000.times do
_('date.formats.short') end; }
# => 0.023993968963623

I18n::YourBackend ?
• You have to implement at least the exact
same features and behavior for Rails I18n
• All extra features won’t be supported in
other backend and should be implemented
externaly
• Will make your 118n/L10n plugin work with
all rails app and plugin
• No more monkey patching !

I18n in Rails
• Currently (Rails2.2):
• AR Validation errors
• Form errors
• Float Number / Currency (output only)
• Time/Date Format (on demand with
I18n.l)
• Time/Date related helpers

I18n in Rails
• Rails in only bundled with :en locale but
since Rails2.2rc2 it comes with a config/
locale folder
• To bootstrap localization of you own rails
app go to http://github.com/svenfuchs/rails-
i18n/tree/master
• Would need a reference page where all keys
used in rails are displayed, currently you have

I18n in Rails: niceties
• Time of custom AR validation message in
class is over:
class User < ActiveRecord::Base
validates_presence_of :name
end
# will look at the different keys in this order
'activerecord.errors.messages.models.user.attributes.name.
blank'
'activerecord.errors.messages.models.user.blank'
'activerecord.errors.messages.blank'
It makes it possible to handle special case
per langage and not in models

I18n in Rails: views
• In views you have the “t” helper:
<%= t \"my.message.here\" %>
<%= t \"my.plural.message.here\", :count => 2 %>
...
Its just an alias to I18n.t

Resources
• The I18n gem: http://github.com/svenfuchs/
i18n/tree
• Rails translation for SimpleBackend: http://
github.com/svenfuchs/rails-i18n/tree/master
• Example rails App: http://github.com/
clemens/i18n_demo_app/tree/master
• Live: http://i18n-demo.phusion.nl/

Thank you
• Big big big thanks to Sven Fuchs and all the
I18n team (matt, ...)
• Any question ?