Question

I am defining a bunch of class variables in my Ruby class and initializing them to a value, but when I print them in my to_url function they are all null, can someone tell me why???

class BarChart < GoogleChart
    @axes_prefix       = "chxt="
    @data_scale_prefix = "chds="
    @type              = "#@@type_prefix" + "bvg"
    @size              = "#@@size_prefix" + "800x375"
    @colors            = "#@@color_prefix" + "4466AA"
    @axes              = "#@axes_prefix" + "x,y,x,y"
    @x_axis_index      = "0"
    @y_axis_index      = "1"
    @x_axis_label_index  = "2"
    @y_axis_label_index  = "3"
    @axes_label_position_prefix = "chxp="
    @axis_range_prefix          = "chxr="

    def initialize(title, data, labels, x_axis_label, y_axis_label)
        @title, @data, @labels, @x_axis_label, @y_axis_label = 
            title, data, labels, x_axis_label, y_axis_label
        super(@title, @type, @size)
        to_url()
    end


    def to_url()
        puts @axes_prefix, @data_scale_prefix, @type, @size, @colors, 
        @axes, @x_axis_label_index, @y_axis_label_index, @x_axis_index, @y_axis_index
    end


    def start()
    b = BarChart.new("CHART", "0,1,2,3,4,5,6,7,8,9", 
    "ZERO, ONE, TWO, THREE, FOUR, FIVE, SIX, SEVEN, EIGHT, NINE", 
    "Zero to Nine", "Numbers").to_s()
    end

if __FILE__ == $0
    start()
end

Any ideas would be great.

Thanks.

Answer 1

1. It’s not a class variables, it’s a instance variables. (@@foo – it’s class variable)
2. You can’t initialize them outside of the methods. Move them to the initialize method, for example.