Atanas Roussev – Senior Java Developer, UI Engineer, Web Developer Resume – Vancouver

I was playing with Ruby and tried HTTP4e on MyRadRails and it worked as a charm.

This is what I call write once run anywhere. Great job Eclipse!

I keep spreading the message. While Java gurus are still faithing on those religious best web framework wars , there is hidden winner already.

The best Java web framework award goes to … drumrolls … Finland.

Vaadin – When I saw it for a first time few months back, I was shocked. That what Java is meant to be – Innovative, slick, sexy.

On this blog the Groovy inventor talks on Scala: Scala as the long term replacement for java/javac?

I am pretty sure web is full of that link, but it a quite an interesting read. So simply spreading the message.

Let’s get back to the Ruby’s Shape , Triangle, Square polymorphism example and translate it to Scala:

object HelloObjects extends Application {
  val shapes = new Array[Shape](3);
  shapes(0) = new Triangle(7,7)
  shapes(1) = new Square(7)
  shapes(2) = new Circle(7)

  shapes.foreach(shape => shape.info)
}

trait Shape {
  def name(): String
  def area(): Double
  def info() = println(name() + " area: " + area())
}

class Triangle(x: Int, y: Int) extends Shape {
  override def name() = "Triangle"
  override def area() = x * y / 2.0
}

class Square(x: Int) extends Shape {
  override def name() = "Square"
  override def area() = x * x
}

class Circle(r: Int) extends Shape {
  val PI = 22 / 7;
  override def area() = PI * r
  override def name() = "Circle"
}

Apparently Rails doesn’t scale and Twitter moved to a JVM compiled solution which is … Scala. Probably Twitter is moving to Lift altogether?

http://www.artima.com/scalazine/articles/twitter_on_scala.html

Coming from Java to Ruby … Have you ever encounter this?

  a = -5
  n = 3
  x = (a % n)

  In Java this would return 2.
  In Ruby though it returns 1.

Reason. Ruby is using different algorythm for modulo:

If you still feel more comfortable with old habits,  you can hack it using abs function:

  a = -5
  n = 3
  x = (a.abs % n)

  Which Ruby will evaluate to 2

Remember your first cup of Object Oriented Java? Shape, Triangle, Circle polymorphism?

Here it’s the kewl Ruby equivalent:

class Shape
  def info
    // prints abstract method name and area. Confusing eh?
    puts "#{name} area: #{area}"
  end
end

class Triangle < Shape
  attr_reader :base, :height

  def initialize(base, height)
    super()
    @base = base
    @height = height
  end 

  def area
    return ((base * height).to_f./ 2)
  end

  def name
    return "Triangle"
  end
end

class Square < Shape
  attr_reader :height

  def initialize(height)
    super()
    @height = height
  end 

  def area
    return (height * height).to_f
  end

  def name
    return "Square"
  end
end

class Circle < Shape
  attr_reader :r
  PI = 22.to_f./7
  def initialize(r)
    super()
    @r = r
  end 

  def area
    return (PI * r * r)
  end

  def name
    return "Circle"
  end
end

if __FILE__ == $0
  g = Triangle.new(7, 7)
  g.info

  g = Square.new(7)
  g.info

  g = Circle.new(7)
  g.info
end

Result is:
Triangle area: 24.5
Square area: 49.0
Circle area: 154.0