From: Jonathan Groll <lists@...>
Date: 2008-10-24T17:39:58+09:00
Subject: Problem with using active support core extensions in my own ruby programs

This code used to perform correctly with activesupport 2.0.2:

#!/usr/bin/ruby
require 'rubygems'
require 'time'
require 'active_support'

class Time
  include ActiveSupport::CoreExtensions::Time::Calculations
end

nxt = Time.now.change(:hour => 7)
nxt = nxt.tomorrow if nxt < Time.now
puts nxt

***
However, with activesupport 2.1.2 it now fails:
/var/lib/gems/1.8/gems/activesupport-2.1.2/lib/active_support/core_ext/time/calculations.rb:270:in
'compare_without_coercion': stack level too deep (SystemStackError)
			    from
			    /var/lib/gems/1.8/gems/activesupport-2.1.2/lib/active_support/core_ext/time/calculations.rb:270:in
			    '<=>'
			    from ./problem_for_ruby.ml:11:in '<'
			    from ./problem_for_ruby.ml:11

The above is obviously caused by the comparison:
if nxt < Time.now

Inside calculations.rb we seem to be getting lost in:
        # Layers additional behavior on Time#<=> so that DateTime and
	ActiveSupport::TimeWithZone instances
        # can be chronologically compared with a Time
        def compare_with_coercion(other)
          # if other is an ActiveSupport::TimeWithZone, coerce a Time
	  instance from it so we can do <=> comparision
          other = other.comparable_time if
	  other.respond_to?(:comparable_time)
          if other.acts_like?(:date)
            # other is a Date/DateTime, so coerce self #to_datetime
	    and hand off to DateTime#<=>
            to_datetime.compare_without_coercion(other)
          else
            compare_without_coercion(other)
          end
        end

compare_without_coercion is an alias:
 alias_method :compare_without_coercion, :<=>

So: how to do this comparison? Is it a good idea to make use of
activesupport's core extensions in my own ruby programs? Is this an
activesupport bug?

Many thanks,
Jonathan Groll