TZInfo – Daylight-savings aware timezone support for Ruby

TZInfo uses the tz database (www.twinsun.com/tz/tz-link.htm) to provide daylight-savings aware transformations between times in different timezones. This is the same database as used for zoneinfo on Unix machines.

The tz database has been imported (using TZDataParser) and turned into a set of Ruby classes (which are packaged with this release).

Example usage

To convert a time in UTC, to a local time in the America/New_York timezone, you can do the following:

require_gem 'tzinfo'
include TZInfo

tz = Timezone.get('America/New_York')
local = tz.utc_to_local(DateTime.new(2005,8,29,15,35,0))

To convert from a local time to UTC, the local_to_utc method can be used:

utc = tz.local_to_utc(local)

To get information about the rules in force at a particular UTC or local time, the Timezone.period_for_utc and Timezone.period_for_local methods can be used. Both of these methods return TimezonePeriod objects. The following gets the identifier for the period (in this case EDT).

period = tz.period_for_utc(DateTime.new(2005,8,29,15,35,0))
id = period.zone_identifier

In all the above examples, instances of Time can be used instead of DateTime. Timezone.utc_to_local and Timezone.local_to_utc both return the type they are passed.

You can get the current local time in a Timezone with the Timezone.now method:

now = tz.now

You can also access Timezones by Country (ISO 3166 country code). The following gets all the Timezone identifiers for the US:

us = Country.get('US')
timezones = us.zone_identifiers

The above covers the most common uses of Timezone and Country. For more detail, see their individual class documentation.

Download

The latest version of TZInfo can be found at

• rubyforge.org/frs/?group_id=894

Documentation can be found at

• tzinfo.rubyforge.org/doc/

Installation

The preferred method of installing TZInfo is through its GEM file (RubyGems required):

% gem install tzinfo-0.0.2.gem

or to automatically download and install:

% gem install tzinfo --remote

License

TZInfo is released under the MIT license.

Issues

• It currently takes an extremely long time to generate all the Ruby Timezone classes from the tz data. This process could do with some optimization.

• Test cases need to be written.

Support

Please contact Philip Ross (phil.ross@gmail.com) if you require assistance or have any suggestions.