Carmen 1.0.0 is now out, after more than a year in beta. This release is a rewrite of the library, separating out the geographic components from the Rails-specific view helpers. If you are using Carmen with Rails, you should check out the carmen-rails library.

The 0.2.x branch contains the previous version of Carmen should you need it for some reason.

Carmen now requires Ruby 1.9. The ruby-18 branch contains the last stable version of Carmen that will run on Ruby 1.8.x.

Carmen 1.0 features the following:

• A new, cleaner API
• More complete data via the iso-codes Debian package (idea borrowed from here)
• A sane approach to internationalization

Carmen is designed to make it easy to access Country and region data. You can query for a country by name or code:

require 'carmen'
include Carmen

us = Country.named('United States')
=> <#Carmen::Country name="United States">

A Country object has some attributes that may be useful:

us.alpha_2_code
=> 'US'

us.alpha_3_code
=> 'USA'

us.code # alias for alpha_2_code
=> 'US'

us.official_name
=> "United States of America"

A Country (and its subregions) can contain subregions. In the US these are states, but other countries have other types of regions:

us.subregions?
=> true

us.subregions.first
  => <#Carmen::Region name="Alabama" type="state">

Country#subregions returns a RegionCollection, which can be queried similarly to a Country to find, for instance, a specific state:

illinois = us.subregions.coded('IL')
=> <#Carmen::Region "Illinois">

Subregions support a smaller set of attributes than countries:

illinois.name
  => "Illinois"

illinois.code
=> "IL"

illinois.type
=> "state"

Some subregions may contain additional subregions. An example of this is Spain:

spain = Country.named('Spain')
andalucia = spain.subregions.first
=> <#Carmen::Region name="Andalucía" type="autonomous community">

andalucia.subregions?
=> true

andalucia.subregions.first
=> <#Carmen::Region name="Almería" type="province">

In order to facilitate support for I18n, Carmen stores the structure of regions separately from the strings that represent a region's names. The default data that ships with Carmen is in the iso_data and locale directories, respectively.

You might want to tweak the data that Carmen provides for a variety of reasons. Carmen maintains an array of paths to load data from in: Carmen.data_paths. The structure of files in each of these paths should mirror those in the iso_data path Carmen ships with.

To add a new country to the system, you would create a directory (let's use my_data as an example), and create a world.yml file inside it. Then add the path to Carman:

Carmen.append_data_path File.expand_path('../my_data', __FILE__)

Elements within the data files are identified using their code values (or, in the case of countries, alpha_2_code). Create a new block for the country you wish to add inside my_data/world.yml:

---
- alpha_2_code: ZZ
  alpha_3_code: ZZZ
  numeric_code: "999"
  type: country

Now, modify the fields you wish to change, and delete the others. Be sure to specify alpha_2_code for countries and code for subregions, as those values are used internally by Carmen to match your customized data with the corresponding data in the default dataset.

Now, Carmen will reflect your personal view of the world:

Carmen::Country.coded('ZZ').type
=> "country"

You will also want to create a localization file with the names for the new region. See the section 'Customizing an existing locale', below.

Existing regions can be modified by copying their existing data block into a new file at the correct overlay path, and modifying the values as desired.

It is also possible to remove an element from the dataset by setting its _enabled value to anything YAML considers false, such as 'false' or 'no':

- alpha_2_code: EU
  _enabled: false

This will cause Carmen to not return that element from any query:

Carmen::Country.coded('EU')
=> nil

Carmen ships with very simple I18n support. You can tell Carmen to use your own I18n backend:

Carmen.i18n_backend = YourI18nBackend.new

The object used as a backend must respond to t with a single argument (the key being looked up). This key will look something like world.us.il.name.

If you use the built in I18n support, you can set the locale:

Carmen.i18n_backend.locale = :es

Each region is assigned a localization key based on the formula world.PARENT_CODE.CODE. The key used for the United States is world.us.

The library ships with a set of YAML files that contain localizations of many country names (and some states). If you want to override any of these values, create a YAML file that contains a nested hash structure, where each segment of the key is a hash:

en:
  world:
    us:
      official_name: These Crazy States

This file can live anywhere, but it is recommended that it be stored in a structure similar to the one Carmen uses for its locale storage.

To tell Carmen to load this file, add the directory it is contained in to the set of locale paths used by the backend:

Carmen.i18n_backend.append_locale_path('/path/to/your/locale/files')

If you are using your own backend, then follow the steps necessary to have it load your additional files instead.

Please read Contributing Data before making any changes to the project's data. It will save you (and me) a bunch of time!

Jacob Morris has created a plugin for Carmen that adds support for demonyms.

Cyle Hunter has created a plugin that adds ISO 4217 currency names to Carmen::Country.