Question

Overview

I am writing a Ruby program that uses data from mysql queries to create chart URLs. A new requirement has recently surfaced where we could need to created graphs with grouped bars in the future. So instead of having one set of data, I could have any number of sets. Right now the constructor for my BarChart object only takes a single array of data, and I am looking Ruby-like ways of allowing more than one array of data.

Current Constructor

    #constructor
    #title          The title of the graph
    #data           The data that will go in the bar chart
    #labels         The labels that match the data
    #x_axis_label   The label for the x axis
    #y_axis_label   The label for the y axis
    def initialize(title, data, labels, x_axis_label, y_axis_label)
        @title, @data1, @labels, @x_axis_label, @y_axis_label = 
            title, data, labels, x_axis_label, y_axis_label

        super(@title, @@type, @@size)
        @url = to_url()
    end

My attempt

My initial thought was to use var args.

    #constructor
    #title          The title of the graph
    #data           The data that will go in the bar chart
    #labels         The labels that match the data
    #x_axis_label   The label for the x axis
    #y_axis_label   The label for the y axis
    def initialize(title, *data, labels, x_axis_label, y_axis_label)
        .....
    end

Is this a decent idea? or is there a better way to go about it?

Thanks

Answer 1

Personally, when you have this many arguments, I would use an options hash.

def initialize(options = {})
  options = { default options here, if applicable }.merge(options)
  ...
end

So that you can construct your class like this:

MyClass.new(:title => "Awesome Graph", :data => [[1,2,3], [4,5,6]], ...)

I find this approach makes your method calls much more readable, so you don’t have a constructor call which has a long sequence of number and string arguments for which the meaning may be difficult to determine. This also gives you a natural way to add an arbitrary amount of optional parameters with default values.