From: Paul Lutus <nospam@...>
Date: 2006-10-27T06:20:16+09:00
Subject: Re: Time without Date

List Recv wrote:

> Is there any class or lib to deal with Times without Date?  (Eg "3:30
> PM" - but I don't want it associated with a date.)
> 
> Ideally, I'd like to:
> * Have clock arithmetic (1 AM minus 90 minutes is 11:30 PM)
> * Convert from DateTime to dateless times (and, by adding a date, back)
> * Store it with ActiveRecord
> 
> Any ideas?

Have you tried the Time class?

#!/usr/bin/ruby -w

is = Time.new

h = 4 # hours

was = is - (h * 60 * 60)

puts "Time now: #{is}\nTime then: #{was}"

Output:

Time now: Thu Oct 26 14:10:41 PDT 2006
Time then: Thu Oct 26 10:10:41 PDT 2006

The Time object is expressed in seconds elapsed since 1/1/1970 00:00 GMT.
Just add or subtract seconds to get what you want. And the 1970 limitation
isn't actually much of a limitation:

irb(main):008:0> t = Time.new - (100 * 60 * 60 * 24 * 365.25)
=> Fri Oct 26 13:16:52 PST 1906

-- 
Paul Lutus
http://www.arachnoid.com