Ruby -- Improved Version

Contributed by Guy N. Hurst

After putting together this comparison, Guy Hurst sent me the following note.

I found your page at http://w3.one.net/~jweirich/oostuff/ to be very interesting.
I have been working with ruby lately, and looked at that version. I realized that I could suggest a shorter version (much shorter) to the provided ruby script.
Basically, by using 'attr_accessor :var' instead of 'attr :var', one can get or set the var using 'instance.var' or 'instance.var=xxx' and dispense with defining/using getVar() or setVar() methods.

Here is Guy's improved version.

Shape class (Shape.rb)

class Shape
    attr_accessor :x, :y

    # constructor
    def initialize(initx, inity)
       @x=initx
       @y=inity
    end

    # move the x & y position of the object
    def moveTo(newx, newy)
       @x=newx
       @y=newy
    end
    def rMoveTo(newx, newy)
       moveTo(newx + @x, newy + @y)
    end
 end

Rectangle class (Rectangle.rb)

require "Shape.rb"

 class Rectangle < Shape
    attr_accessor :width, :height

    # constructor
    def initialize(initx, inity, initwidth, initheight)
       super(initx, inity)
       @width=initwidth
       @height=initheight
    end

    # draw the rectangle
    def draw
       print("Drawing a Rectangle at:(", @x, ",", @y,
          "), width ", @width, ", height ", @height, "\n")
    end
 end

Circle class (Circle.rb)

require "Shape.rb"

 class Circle < Shape
    attr_accessor :radius

    # constructor
    def initialize(initx, inity, initradius)
       super(initx, inity)
       @radius=initradius
    end

    # draw the circle
    def draw
       print("Draw a Circle at:(", @x, ",", @y,
          "), radius ", @radius, "\n")
    end
 end

Polymorphism test (Polymorph.rb)

require "Rectangle.rb"
require "Circle.rb"

 # create a collection containing various shape instances
 scribble = [Rectangle.new(10, 20, 5, 6), Circle.new(15, 25, 8)]

 # iterate through the collection and handle shapes polymorphically
 scribble.each do |ashape|
    ashape.draw
    ashape.rMoveTo(100, 100)
    ashape.draw
 end

 # access a rectangle specific function
 arectangle = Rectangle.new(0, 0, 15, 15)
 arectangle.width=30
 arectangle.draw

Jim Weirich / jweirich@one.net