Martin Fowler's Runt library is really handy for date/time comparisons, and this code works great in an irb console:

require 'runt'
include Runt

r_start = PDate.month(2010,12)
r_end = PDate.month(2011,12)
range = DateRange.new(r_start,r_end)
o_start = PDate.month(2010,11)
o_end = PDate.month(2012,2)
o_range = DateRange.new(o_start,o_end)

range.overlap?(o_range)

but if I add the Runt gem to my Rails 2.3.5 app and try to run the same commands in script/console, I get this error:

NoMethodError: undefined method `to_datetime' for Mon, 01 Nov 2010 00:00:00 +0000..Wed, 01 Feb 2012 00:00:00 +0000:Runt::DateRange

from /Users/jacob/work/matchbook/vendor/gems/runt-0.7.6/lib/runt/sugar.rb:130:in method_missing' from /Users/jacob/work/matchbook/vendor/rails/activesupport/lib/active_support/core_ext/date_time/calculations.rb:120:in <=>' from /Users/jacob/work/matchbook/vendor/gems/runt-0.7.6/lib/runt/pdate.rb:91:in <=>' from /Users/jacob/work/matchbook/vendor/gems/runt-0.7.6/lib/runt/daterange.rb:34:in member?' from /Users/jacob/work/matchbook/vendor/gems/runt-0.7.6/lib/runt/daterange.rb:34:in `overlap?' from (irb):10

Has anyone encountered this error before, or does anyone know how to begin debugging this? I've tried looking at the spaceship operator in the ActiveSupport calculations module, but I can't figure out how to pick apart the problem.

Thanks very much for your help,

Jacob