10 July 2013

* a response to Why Ruby Rocks

In case you are new to Scala, don’t take it as a representing case, this is not idiomatic scala, and there are much better featrues making Scala a great language in my opinion. Having said that, here are the 2 examples in the “Why Ruby Rocks” post, implemented in Scala:

Automatic getters / setters

Just like in Ruby, the boilerplate of writing getters / setters for simple properties is eliminated. Scala automatically generates a getter and setter method (named the same as the member)

class Person(var sanity:Int = 50)

object Main extends App {
  val programmer = new Person(50)
  programmer.sanity += 1000000

This is equivalent more or less to Ruby’s attr_accessor :sanity

The syntactic desugar version of it is something (very roughly) like this:

class Person(private[this] var _sanity:Int = 50) {
  def sanity:Int = this._sanity
  def sanity_= (sanity:Int) {this._sanity = sanity}
Note - idiomatic Scala discourages mutable objects, so prefer using val which is final and will only generate an automatic getter

Dynamic methods

The second example was Ruby’s method_missing, here is the Scala equivalent more or less

import scala.language.dynamics
class Useless extends Dynamic {
  def applyDynamic(name: String)(args: Any*) {
    println(s"Sorry, I wish I could $name...")
    if (!args.isEmpty) {
      println(s"Here, you can have your ${args.mkString(", ")} back.")

object Main {
  def main(args: Array[String]) {
    val useless = new Useless

This will print pretty much the same as the Ruby example

Sorry!, I wish I could reticulate...
Here, you can have your splines back.
Note - don't do this unless you have a very good reason, it has performance and code smell issues

There are of course many other features that make Scala “rock”, which probably deserve a separate post.

blog comments powered by Disqus