very simple class to make calculation spans of time super easy. Inspired by .NET's TimeSpan class, still lots of room for improvement! For Rails I recommend putting it in /config/initializers.

TimeSpan.rb

class TimeSpan
	attr_accessor :milliseconds

	def self.from_milliseconds(milliseconds)
		me = TimeSpan.new
		me.milliseconds = milliseconds
		return me
	end

	def self.from_seconds(seconds)
		TimeSpan.from_milliseconds(seconds.to_d * 1000)
	end

	def self.from_minutes(minutes)
		TimeSpan.from_milliseconds(minutes.to_d * 60000)
	end

	def self.from_hours(hours)
		TimeSpan.from_milliseconds(hours.to_d * 3600000)
	end

	def self.from_days(days)
		TimeSpan.from_milliseconds(days.to_d * 86400000)
	end

	def self.from_years(years)
		TimeSpan.from_days(years.to_d * 365.242)
	end

	def self.diff(start_date_time, end_date_time)
		TimeSpan.from_seconds(end_date_time - start_date_time)
	end

	def seconds
		self.milliseconds.to_d * 0.001
	end

	def minutes
		self.seconds.to_d * 0.0166667
	end

	def hours
		self.minutes.to_d * 0.0166667
	end

	def days
		self.hours.to_d * 0.0416667
	end

	def years
		self.days.to_d * 0.00273791
	end
end