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2011-02-06

Hello Ruby

Recently, I've been looking into the Ruby Programming Language and like most programmers I started by writing a "Hello World" program. Now let me say that I am not a fan of most Hello_World programs simply because I don't think they really give much information to the viewer of the code, so I thought I should share the code that I wrote.

There were a few programming language features that I thought should be included in my code.

An Object Oriented class

Quite a bit of my coding is Object Oriented and since most anything I program in the future using Ruby will be Object Oriented, this was a must.

A class that extends the functionality of the previous class

Writing my own classes is good and dandy, but very often I need to extend a base class from and included code library with additional functionality and I wanted to see what sort of coding requirements Ruby has for extending classes.

some sort of array thingy

Each programming language has various names for ways to store a collection of data: list, dictionary, hash table, array, and a few other things that I usually forget because I don't pay much attention to nomenclature. Anyway, I always end up having to program some way to deal with a list of words or numbers or something, so I made sure to include an array in my program.

Enter the Ruby

#!/usr/bin/env ruby

#define a class to print out some words
class PrintThing
  def initialize
    #we need a variable to hold the words to be printed
    @words = [] #use an empty array
  end
  
  #define a function to set the @words
  def set_words(words)
    @words = [words]
  end
  
  #define a function to output all of the elements of the words array 
  def print_words()
    puts @words.join( " " )
  end
end

#extend the printthing class to be more advanced
class AdvancedPrintThing < PrintThing
  #define a function to add an element to the words array
  def add_word( word )
    @words.push( word )
  end
  
  #define a function to truncate the words array
  def clear()
    @words = []
  end
end

if __FILE__==$0
  #create an instance of the PrintThing
  pt = PrintThing.new
  #set some words
  pt.set_words( "Hello World" )
  #print the words
  pt.print_words()
  #create an instance of the AdvancedPrintThing
  apt = AdvancedPrintThing.new
  #set some words
  apt.set_words( 'Howdy Buddy!' )
  #print the words
  apt.print_words()
  #clear the word list
  apt.clear()
  #add a bunch of single words
  apt.add_word( 'How' )
  apt.add_word( 'are' )
  apt.add_word( 'you?' )
  #print the words
  apt.print_words()
end

What I learned

  • Defining a class is easy and a new class should have a constructor method named "initialize" if the class needs to do something when a new instance of the class is created
  • Extending a class can be done with the "<" symbol, so to code that class A extends class B is as simple as "class A < B".
  • a variables scope is determined by the variable's starting character.
    $ for global variables
    @ for instance variable
    @@ for class variables
    While this can look confusing at first, I like being able to determine at a glance exactly what the scope of a variable is.
  • There was no need to worry about code indentation. Ahhh relief.
  • Ruby does not create byte-code when an ruby program is run. sigh of disapproval

All things considered, I like the language and there is some rather impressive documentation available at http://www.ruby-doc.org/

Now quit reading, and go find yourself a programming project.

Hello World in Ruby from jezra.net
Comments
2011-04-10 senshikaze:
Have you checked out "why's poignant guide to ruby"? It is hilarious at least. chunky Bacon!

http://mislav.uniqpath.com/poignant-guide/book/chapter-1.html
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