include? vs. cover? vs. between?

include-vs-cover-vs-between.rb

require 'date'
require 'benchmark'

n = 1_000_000
start_date = Date.new(2012, 01, 01)
end_date   = Date.new(2012, 03, 01)
act_date   = Date.new(2012, 02, 01)

Benchmark.bm(10) do |x|
  x.report('include?') do
    n.times do
      (start_date..end_date).include? (act_date)
    end
  end
  x.report('cover?') do
    n.times do
      (start_date..end_date).cover? (act_date)
    end
  end
  x.report('between?') do
    n.times do
      act_date.between?(start_date, end_date)
    end
  end
end

output.txt

js@horadrim [~/Code] % ruby ./include-vs-cover-vs-between.rb  
                 user     system      total        real
include?    38.910000   0.130000  39.040000 ( 40.826650)
cover?       1.100000   0.000000   1.100000 (  1.147182)
between?     0.630000   0.010000   0.640000 (  0.642790)

i don't understand what would make between? better than cover?. any idea?

@fnando on top of what @bradland said, I think you are comparing apples and oranges. The initial tests are assuming a static object that already has the values setup, however you are calling to_i during each run for all variables. It would be more in line with the original tests if you also set all of these values before the test. In many cases, if somebody is wanting to do a lot of between tests, either the act_date or the start-end date combination won't be changing.

However, unless all three are not changing, between is still going to win. :)