a patch to fix compass raising error when using 'transparent' keyword for gradiention: 'Expected a color. Got: transparent'

gradient_support.rb

## If you are using under a rails project,
## I recommend to put this script onto config/initializer instead of applying the patch

module Compass::SassExtensions::Functions::GradientSupport

  class ColorStop < Sass::Script::Literal

    def initialize(color, stop = nil)
      self.options = {}
      if color.is_a?(Sass::Script::String) && color.value == 'transparent'
        color = Sass::Script::Color.new([0,0,0,0])
        color.options = {}
      end
      unless Sass::Script::Color === color || Sass::Script::Funcall === color
        raise Sass::SyntaxError, "Expected a color. Got: #{color}"
      end
      if stop && !stop.is_a?(Sass::Script::Number)
        raise Sass::SyntaxError, "Expected a number. Got: #{stop}"
      end
      self.color, self.stop = color, stop
    end

  end

  module Functions

    def color_stops(*args)
      Sass::Script::List.new(args.map do |arg|
        case arg
        when ColorStop
          arg
        when Sass::Script::Color
          ColorStop.new(arg)
        when Sass::Script::List
          ColorStop.new(*arg.value)
        when Sass::Script::String
          ColorStop.new(arg)
        else
          raise Sass::SyntaxError, "Not a valid color stop: #{arg.class.name}: #{arg}"
        end
      end, :comma)
    end

  end
end

gradient_support.rb.patch

--- gradient_support_org.rb	2012-02-02 19:30:18.000000000 +0900
+++ gradient_support.rb	2012-02-02 19:31:28.000000000 +0900
@@ -8,6 +8,11 @@
       [color, stop].compact
     end
     def initialize(color, stop = nil)
+      self.options = {}
+      if color.is_a?(Sass::Script::String) && color.value == 'transparent'
+        color = Sass::Script::Color.new([0,0,0,0])
+        color.options = {}
+      end
       unless Sass::Script::Color === color || Sass::Script::Funcall === color
         raise Sass::SyntaxError, "Expected a color. Got: #{color}"
       end
@@ -141,7 +146,7 @@
     end
 
     def initialize(position_or_angle, color_stops)
-      unless color_stops.value.size >= 2
+      unless color_stops.value && color_stops.value.size >= 2
         raise Sass::SyntaxError, "At least two color stops are required for a linear-gradient"
       end
       self.position_or_angle = position_or_angle
@@ -234,6 +239,8 @@
           ColorStop.new(arg)
         when Sass::Script::List
           ColorStop.new(*arg.value)
+        when Sass::Script::String
+          ColorStop.new(arg)
         else
           raise Sass::SyntaxError, "Not a valid color stop: #{arg.class.name}: #{arg}"
         end