This Sass extension adds the ability to strip or append units to a number with ease, which can be annoying in Sass. Strip units works on all unit values, eg. 12in, 0.56pt, 800px, 34em, except % but that is already easy to add to unitless numbers.

units_sass_extensions.rb

#!/usr/bin/env ruby

# To implement extension, run this command in a shell:
#   $ sass -i -r ./units_sass_extension.rb
# Or require it in compass config
#   require './units_sass_extension'
module Sass::Script::Functions

  # 
  # Strips units from a value, e.g. '10px' or '10in' becomes 10
  # @param number [Number] Number is a subclass of Sass::Script::Literal
  #                        
  # @return [Number]
  def strip_units number
    assert_type number, :Number
    Sass::Script::Number.new number.value.to_f
  end
  declare :strip_units, :args => [:number]

  # 
  # Appends units to a number, e.g. 10px or 10in
  # @param number [Number] Number is a subclass of Sass::Script::Literal
  # 
  # @return [String]
  def append_units number, units
    assert_type number, :Number
    assert_type units, :String
    number = "#{strip_units(number).value}#{units}"
    Sass::Script::Parser.new(number, 0, 0).parse
  end
  declare :append_units, :args => [:number, :string]

end