From: "Alexandru E. Ungur" <alexandru@...>
Date: 2007-02-06T22:24:40+09:00
Subject: Re: Calculating a future date

>>> sender: "Toine" date: "Tue, Feb 06, 2007 at 08:00:06PM +0900" <<<EOQ
> Date.today + 31 and Time.now + 31*24*60*60 yield the same results.
Just beware that although they yield the same result they do it at
*very* different speeds:

~>> cat date_vs_time.rb 
require 'benchmark'
require 'date'

n = 100_000
Benchmark.bm do |x|
  x.report { n.times do a = Date.today+31; end }
  x.report { n.times do a = Time.now+2678400; end }
end


~>> ruby date_vs_time.rb 
      user     system      total        real
 24.300000   0.760000  25.060000 ( 31.808122)
  0.410000   0.440000   0.850000 (  0.971718)


So, whenever you can get away with Time, use it. Only use Date when 
you have to.


Cheers,
Alex