= TZInfo -- Daylight-savings aware timezone support for Ruby

TZInfo[http://tzinfo.rubyforge.org] uses the tz database 
(http://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 modules (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 'tzinfo'
  
  tz = TZInfo::Timezone.get('America/New_York')
  local = tz.utc_to_local(Time.utc(2005,8,29,15,35,0))

Note that the Time returned will look like it is UTC (Time.zone will return 
"UTC"). This is because it is not currently possible to change the offset of 
an individual Time instance.
  
To convert from a local time to UTC, the local_to_utc method can be used. 

  utc = tz.local_to_utc(local)

Note that the timezone information of the time you pass in is ignored. The
following two lines will return the same result regardless of the local 
timezone:

  tz.local_to_utc(Time.local(2006,6,26,1,0,0))
  tz.local_to_utc(Time.utc(2006,6,26,1,0,0))
  
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

All methods in TZInfo that take a time can be used with either Time, DateTime
or Integers (Time#to_i). The return type will be the same as the type passed in.
  
You can also access Timezones by Country (ISO 3166 country code). The following 
gets all the Timezone identifiers for the US:

  us = TZInfo::Country.get('US')
  timezones = us.zone_identifiers
  
The zone_info method of Country provides an additional description and
location for each Timezone in the Country.
  
The above covers the most common uses of Timezone and Country. For more detail,
see the API documentation for the individual classes.


== Download

The latest version of TZInfo can be found at

* http://rubyforge.org/frs/?group_id=894

API documentation can be found at 

* http://tzinfo.rubyforge.org/doc/


== Installation

The preferred method of installing TZInfo is through the GEM file (RubyGems[http://docs.rubygems.org/] required):

  % gem install tzinfo-x.y.z.gem
  
or to automatically download and install:

  % gem install tzinfo --remote
  

== License

TZInfo is released under the MIT[http://opensource.org/licenses/mit-license.html] license.


== Support

Please post to the TZInfo Users mailing list (http://rubyforge.org/mailman/listinfo/tzinfo-users)
if you require assistance or have any suggestions.

Alternatively, you can contact the author Philip Ross directly at phil.ross@gmail.com.