Pretty quantifiable measurements which feel like ActiveSupport::Duration.
Access whichever included attributes you want like so:
require 'quantified/mass'
require 'quantified/length'
Add methods to Numeric (only plural, must correspond with plural unit names):
Mass.numeric_methods :grams, :kilograms, :ounces, :pounds
Length.numeric_methods :metres, :centimetres, :inches, :feet
Then you can do things like this:
1.feet == 12.inches
# => true
18.inches.to_feet
# => #<Quantified::Length: 1.5 feet>
(2.5).feet.in_millimetres.to_s
# => "762.0 millimetres"
You can easily define new attributes. Here's length.rb:
module Quantified
class Length < Attribute
system :metric do
primitive :metre
one :centimetre, :is => Length.new(0.01, :metres)
one :millimetre, :is => Length.new(0.1, :centimetres)
one :kilometre, :is => Length.new(1000, :metres)
end
system :imperial do
primitive :inch
one :inch, :is => Length.new(2.540, :centimetres)
one :foot, :plural => :feet, :is => Length.new(12, :inches)
one :yard, :is => Length.new(3, :feet)
one :mile, :is => Length.new(5280, :feet)
end
end
end
You can add a custom coder to an ActiveRecord model to deserialize attributes:
class Package < ActiveRecord::Base
serialize :weight, Quantified::Mass.ounces
serialize :length, Quantified::Length.inches
serialize :width, Quantified::Length.inches
end