From Java to Ruby 1

All right! After dabbling around in Java for more than a decade now, working in C++, Lisp and Smalltalk even before that, it's now time to expand the horizon a bit and get my hands on Ruby.

It's promised to make things easier, faster and to speed up the development process significantly.

Assuming you have some deeper knowledge about object-orientation in general and in Java in particular, let's start with a simple example: A trivial Java class vs. its version in Ruby.

Here it is in Java - I won't use comments to save some space:

public class Person {
 private String name;
 private int age;

 public Person(String name, int age) {
     this.name = name;
     this.age = age;
 }

 public String getName() {
     return name;
 }

 public int getAge() {
     return age;
 }

 public void setAge(int age) {
     this.age = age;
 }

 public String toString() {
     return "A person named " + name + " aged " + age;
 }
}

Nothing special here, just two instance fields, "name" is read-only (just a get method) and "age" is read/write (both get and set method).

In Ruby this seems to be a bit more condensed:

class Person
  attr_reader :name, :age
  attr_writer :age
  def initialize(name, age)
    @name = name
    @age = age
  end
   def to_s
    "A person named #{@name} aged #{@age}"
  end
end

Yep! It is more "condensed". Two reasons: No static typing (I love that!) and the nice idea of declaring the accessibility of a variable directly (attr_reader means read access, attr_writer means write access).

Also nice: Disambiguating instance fields by the "@" prefix - makes is optically clear you're referring to the instance field and not any old identifier that suddenly "slipped into the scope".

Mains and stuff: next post.

CU