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Ruby: Most Popular Articles

These articles are the most popular over the last month.
How to Fix Missing Class or Module Errors
Problem: You encounter an error reading NameError: uninitialized constant Something or NameError: uninitialized constant Object::Something (with various class names in place of Something).
A Quick Guide to Creating and Using Hashes in...
This article explains and teaches how to use a associative arrays (hashes) as a way to store multiple variables in one data structure.
Be Notified of New Twitter Updates by IM
Be notified of Twitter updates by IM, using this Ruby script. It's a pain to switch to a Web browser every you want to check your Twitter account. This script solves that by sending you an instant message (IM) using the Jabber protocol when there's something new to see on Twitter.
What Every Coder Should Know About Running Ruby...
Learn how to use the command line interface on Windows, Linux and OS X to run rb files and use the interactive Ruby program. Page 2.
How to Create Arrays in Ruby
This article explains and teaches how to use a arrays as a way to store multiple variables in one data structure.
A Quick Guide to Forming Command Line Arguments...
Use command-line arguments to pass parameters to your Ruby scripts from the command line.
How to Use OptionParser: Ruby's Powerful...
Ruby comes equipped with a powerful and flexible tool to parse command-line options, OptionParser. The class is an alternative to GetoptLong for analyzing command line options.
Using the 'split' Method in Ruby
String manipulation using the split method in Ruby. Split strings into a list of substrings.
How to Use 'Loops' in Ruby (While, Until, Each,...
Loops, including while and include loops, are one of the most commonly used constructs in computer programs. Page 2.
A Quick Guide to Using Environmental Variables...
Using environment variables in Ruby.
Getting Gaming With Rubygame
Loading images from files and displaying them om the screen is the one of the most basic things you can do in game programming. Luckily, Rubygame makes this really simple.
Creating a URL Shortener in Rails
The following is a list of articles that will show you how to write, style and deploy a URL shortener (like TinyURL) application in Ruby on Rails.
The Main Loop
The main loop is the heartbeat of any game, and is the first thing you need to learn to start making your own games.
How to Use Comments for Ruby Code
Use comments to annotate your Ruby code.
Here's What Ruby Is
What type of language is the Ruby programming language?
Splitting Strings
Unless user input is a single word or number, that input will need to be split, or turned into a list of strings or numbers.
How to Use Case (Switch) Statements in Ruby
The case statement is a control structure that is usually quite limited in other programming langauges. However, it's quite powerful and flexible in Ruby.
A Quick Guide to Installing Ruby on Linux
How to install Ruby on the Linux operating system.
A Simple Guide to Using the Command Line in Ruby
How to use the command line interface on Windows, Linux and OS X to run Ruby scripts and use the interactive Ruby program.
How to Use String Substitution in Ruby
class="no-js" itemscope itemtype="http://schema.org/Article" > itemprop="description" >Splitting a string
How to Create a URL Shortener in Ruby on Rails...
URL shortening is a useful feature for any Rails application. Making it easy for people to share links to your content is always a good thing.
Using Attributes
There are two basic things you can do with an object: call a method on it and access an attribute. Ruby doesn't make a distinction between these things, but it does give you some tools to make some methods act like attributes.
NameError: undefined local variable or method...
Problem: You encounter an error reading NameError: undefined local variable or method `a' for # or NameError: undefined local variable or method `a' for main:Object (with various identifiers in place of 'a').
Using Strings
Using and manipulating strings and substrings in Ruby. Page 4.
Wondering if You Should Overlook The "Require"...
The 'require' method is the reusable code mechanism in Ruby. It allows you to import other source files into your programs.
Tk Widgets
How to use some of the most basic Tk widgets.
Progress Bars with the ruby-progressbar Gem
How to use the ruby-progressbar gem to display progress bars on the command line.
How Does Ruby Compare to Python?
How do Ruby and Python compare in terms of features, form and function?
Ruby on Rails 3 Tutorial: Learn Rails by Example
Ruby on Rails 3 Tutorial: Learn Rails by Example by Michael Hartl is a hands on introduction to not only Ruby on Rails but all the related software and services many Rails developers use such as Git, Github, Heroku and RSpec. There are no long-winded discussions on theory or REST or MVC, each and every part of every chapter is a hands on exercise in building a Rails application. This book is recommended for anyone who prefers a hands on approach to learning.
Adding Files to a Repository
How to add files to a Git repository.
How to Install Ruby
How to install the Ruby interpreter on Windows, Linux and OS X.
Using the Logger Library--How to Write Log...
How to use the logger library to create and write to log files in Ruby.
How to Use 'OptionParser' for Command Parsing...
Using OptionParser to parse command line options is a preferable alternative to GetoptLong or looking through ARGV manually. But how do you use it?
Installing RVM on Linux
Installing the Ruby Version Manager (RVM) on Linux. Page 2.
Version Control and a Solid Editor
Now that you have Linux up and running, and you have Ruby, time to add the two most essential parts of any Rubyist's toolbox: version control and a good editor. Page 3.
RubyMine 5.0
I've always been a Vim person. Just give me a good solid editor and I'll take it from there. But I decided to give RubyMine a good honest try, and here's what I think about it.
Mapping Arrays
Iterating over arrays isn't the only trick up Ruby's sleeve. Having the ability to map arrays (and other enumerable collections) is a powerful feature.
How to Use 'DIR.GLOB' with Directories in Ruby
In the previous article in this series, we discussed the basics of the Dir class. Particularly useful was the Dir.for each method for iterating over all files in a directory. However, this only goes so far. What if you want to iterate over only some files (for example, just XML files) in a directory?
A Simple Guide to Using Aliases in Ruby
Aliasing is a powerful Ruby feature that allows more than one method to be referred to by multiple names. This can be used to give a programmer more expressive options or to create copies of a method, allowing you to change the behavior of a class.
How to Install JSON Gem in Ruby
It's easy to jump into parsing and generating JSON in Ruby with the json gem. It provides an API for parsing JSON from text as well as generating JSON text from arbitrary Ruby objects. It's easily the most used JSON library in Ruby.
Step 3: Authentication with Devise
Before we get too invested in our blog, we need to set up some authentication. We'll be using the popular and capable Devise gem to handle authentication.
How to Use 'Ternary' (Conditional) Operators in...
class="no-js" itemscope itemtype="http://schema.org/Article" > itemprop="description" >The ternary (or
Quick Rails 4 Blog Tutorial
What do you do when a new version of Rails comes out? Build a blog, of course. The blog is kind of the hello, world application of the web application world.
Creating Hashes from Arrays
How do you create hashes from tabular data? There are a few ways, but there's a way built into Ruby that fits onto a single line.
Making Deep Copies in Ruby
It's often necessary to make a copy of a value in Ruby. While this may seem simple, and it is for simple objects, as soon as you have to make a copy of a data structure with multiple array or hashes on the same object, you will quickly find there are many pitfalls.
Generating Random Numbers in Ruby
It's often useful in games, simulation and unit testing to generate random numbers, Ruby provides easy access to a pseudo-random number generator.
How to Install Ruby's Development Environment...
In the past, the Ruby “One-Click Installer” was the primary choice for installing Ruby on Windows. However, the One-Click Installer fell into disrepair and was eventually abandoned. Something new was needed, and thus, RubyInstaller was born.
Optional Method Parameters with Hashes
Using hashes to simulate optional named parameters in methods.
Net::SSH--The SSH (Secure Shell) Protocol
Net::SSH is a way for Ruby to interact with SSH (Secure Shell) protocol. It relies on the OpenSSL library for encryption.
Instantiation and the Initialize Method
Ruby objects are instantiated using the Class.new method, and initialize using their own initialize methods.
Instance Variables
Instance variables are some of the most common and important variables types in Ruby. They begin with the at sign (@) and allow objects to track their internal state.
How Use RMV to Install Ruby On OS X Snow Leopard
OS X has pretty easy access to a GCC development environment installed with XCode (an IDE and development
25 Gem Commands for RubyGems
The gem command is one of the most used Ruby-related commands. This article shows 25 Gem Commands and their functions.
Install Ruby on Windows
How to install the Ruby interpreter on the Windows operating system.
What is Ruby?
New to Ruby? Or even to programming? Find out what Ruby really is (and isn't) and why you should (and shouldn't) use it.
How Does Ruby Compare to the Java Programming...
What features do Ruby and the Java programming language share? How are they alike and how are they different?
Adding and Installing Gems from the Ruby Gems...
Learn to search the Ruby Gems repository to find gems to add and install to your library.
The 10 Fantastic Free Ways to Learn Ruby
Sometimes the old adage rings true: the best things in life are free. If you've wanted to learn a little Ruby, but haven't been able to fit a programming course into your budget, don't worry. There are a number of places on the Web to begin your learning, without sacrificing money or quality.
Getting Started with Bundler
The basics of using Bundler are very trivial, you can be up and running in just a few minutes.
Can I add empty directories to Git repositories?
Can I add empty directories to Git repositories?
Mutexes in Ruby
Since we're talking about threads, we have to talk about mutexes.  A Mutex is the only practical way to prevent race conditions (where more than one thread
Boolean Operators
While simple boolean expressions will get you pretty far, you'll soon find yourself wanting to act on more than one condition. For that you'll need boolean operators.
4 Ways Ruby is Better Than Your Programming...
A comparison of Ruby to other programming languages, including Perl, Java, Python and PHP.
CSV Example: Parsing CSV
A crash course on what CSV is, what it is used for and how it is parsed. A method for parsing CSV files using only Ruby's built-in string methods is presented and discussed.
5 Must Know Features of the Ruby Language
If you're going to program in the Ruby language, there are some basic features you absolutely must know. Here are the Top 5.
Keyword Arguments
Until Ruby 2.0, Ruby has not had true keyword arguments. You could simulate them using a hash, but as of Ruby 2.0 there's no longer any need to do that.
How to Install Gems from Git Repositories in Ruby
How to install gems from git repositories.
Understanding 'String Literals' in Ruby
The basics of strings, string interpolation, single and double quotes, escape sequences and alternate string literal syntaxes.
Step 2: Integrating a Wordpress Theme
The scaffold generator gave us something rather spartan, let's spruce this up by adapting a Wordpress theme to work with our shiny new blog.
Block Parameters and Yielding
class="no-js" itemscope itemtype="http://schema.org/Article" > itemprop="description" >Block parameters
Two Dimensional Arrays in Ruby
We'll use a two dimensional array to represent the 2048 game board, but how do we create a 2D array in Ruby?
What's New in Rails 4?
Now that Rails 4 is out, let's see what's new.
Constant Variables
class="no-js" itemscope itemtype="http://schema.org/Article" > itemprop="description" >The speed of light
Iterating Over Strings
It's not a very common thing in Ruby. You have more sophisticated string tools (such as split or scan), but there are times when you'd want to iterate over the characters in a string. Unicode complicates this matter, but Ruby makes it simple.
What is Cloud Computing?
What is cloud computing? Interviews with industry experts help us define cloud computing, software as service, platform as service and more.
Rails Blog Tutorial - Allowing Comments
Part four of the Ruby on Rails blog tutorial shows you how to create a comments table to allow users to comment on your blog posts.
Cloud Computing and Ruby: Interviewing Hampton...
Why are cloud computing and Ruby on Rails a good match? Let's hear what Hampton Catlin, author of HAML and Wikipedia's head Ruby/mobile architect has to say!
Global Variables
Global variables are not often used in Ruby, however, you should at least understand their usage should you ever encounter them.
Base64 in Ruby
Base64 is a way to represent any data as ASCII data. Ruby provides a few handy functions to encode and decode Base64.
Using Git With Ruby on Rails
You don't have to use version control, but you should be. In the past, version control software has been large, clunky, required servers and really was only used when working in groups. But with Git, it's so easy that you really have no excuse, you should be using version control.
What is Rack?
There’s a lot of talk about Rack , but unless you’re a framework author yourself, you rarely see it. So what is Rack? And why, as an application developer, should you care about it?
Riding Shotgun with Sinatra
Now that you can write controller logic and views and Haml, you can start putting together some more complex application. There's one very annoying thing though: Sinatra does not reload its code whenever you make a change. If you make a change, you have to stop and restart the server. This is just an extra step and generally an annoyance. This where shotgun comes in.
Hello, Sinatra! Using Sinatra in Ruby
How to get started in Sinatra, including how to use actions, parameters, ERB and views.
What is Ruby on Rails?
Learn about the concepts of Ruby on Rails, a Model-View-Controller framework for creating database-driven websites in Ruby.
Creating and Distributing Gems with Bundler
Creating Ruby gems has always been a bit of a pain. When you get right down to it, it's not a hard thing to do, but it's easy to forget how if you don't do it often enough. There are quite a few gems to help you write other gems, but if you're using Rails 3, there's already a gem on your system that does this: Bundler.
How to Use and Create Blocks in Ruby
How to use blocks in Ruby.
Sorting Arrays
One of the most common tasks when dealing with arrays is to sort them. Luckily, Ruby makes this simple and flexible.
Load Vs. Require
You probably know about the 'require' method (yes, it is a method, it's not a keyword), but what about the 'load' method? What's so different about it?
Making a Text Adventure Game in Ruby
Text adventure games were a very popular game genre on minicomputers and microcomputers from the 1970's through the 1990's. This article series will take you through each step of making a text adventure game in Ruby.
Net:SSH--Executing Programs with Net::SSH
Running programs with Net::SSH is simple enough. The Session object gives you two convenient methods with which to accomplish this task.
A Beginner's Guide to Creating a Blog in Ruby
Part one of the Ruby on Rails blog tutorial focuses on creating a Rails project and scaffolding a basic blog post data structure.
Overlooking Input and Output? Using the Input /...
Input and output methods are often overlooked by many Ruby programmers. How often have you used the <b>gets</b> and <b>puts</b> methods without giving them a second glance? Learn all the features of these methods to better put them to use in your code.
What is Sinatra?
Sinatra is a web framework. Simply put, it's a library that allows you to write web applications with a minimum of red tape.
Sending Keystrokes with Win32
Great, now we know how to get to the Win32 API.  Now, on to sending keystrokes using the Win32 API.  Easy, right?  Not really.  It's not that hard, but it's not
extconf.rb:1:in `require': no such file to load...
Problem: You're trying to install a gem and you encounter an error reading no such file to load -- mkmf. This doesn't always occur, only when you're trying to install gems with native C code that must be compiled.
NoSQL and Document Oriented Databases
Chances are, you've spent your entire database life with relational databases. Data gets organized into columns, and stored in rows. You manipulate data with SQL (Structured Query Language) and there's really no other way to do it. There are competing SQL servers out there (MySQL, SQLite, etc), but they all more or less operate in the same way. But there's much more out there than SQL databases, especially with all the new software in the past few years.
What's New in Ruby 1.9.1? -The Lambda Operator
Among the new features in release of Ruby 1.9.1 is the Lambda operator, a shortcut used to make nameless methods. Learn how to use this feature introduced in Ruby 1.9.1.
Serialization in Ruby: Marshal
Serializing an object is to convert an object to a byte stream and either store that object for future loading, or sending to another program to be loaded there. There are several common ways to serialize objects in Ruby. The Marshal module is used less often than the other methods, but it's included in the standard library.
Reading Files
Ruby programs rarely exist in their own little world. And while many choose to communicate over the internet, there's still plenty of need to access plain old files.
Using Temporary Files
There are many hidden pitfalls when using temporary files. Ruby's Tempfile class solves many of these.
Retrieving a Tagged Release
Once you have releases tagged in the repository, it will be useful to retrieve tagged releases. For example, I want to see if a bug was present in version 0.3, so I'll want to retrieve version 0.3 and run it. Git, of course, makes this easy.
The Heroku Hacker's Guide by Randall Degges
comes in. The Heroku Hacker's Guide doesn't aim to be a complete reference (and since cloud computing
Using Rack
In the previous article, you learned what Rack is. Now, it’s time to start using Rack and serve up some pages.
How to Install and Use Ruby's Tk Toolkit
Directions of how to install the Tk GUI and its Ruby bindings on Windows, Linux and Mac OS X.
What's new in Ruby 2.1.0: Under the Hood
What's new in Ruby 2.1.0? There are two new features under the hood that you may not know about: Method caching and an enhanced garbage colllector.
Quick Tip: Install Gems Faster
Some larger projects, especially Ruby on Rails, come with quite a bit of documentation. This is good, documentation is good, but the code that processes this documentation (RDoc) into HTML and ri format is not exactly speedy. On slower computers, or with larger projects, the time this takes becomes and annoyance.
How to Use the Twitter Gem for Ruby
Using the Twitter RubyGem, making API requests to Twitter is even easier than using the twitter method.
The Curious Case of the Flip-Flop
The flip-flop operator is a strange case indeed: part range, part conditional.
Using Haml with Sinatra
How to use Haml to create Sinatra views and layouts. Page 3.
Cryptographic Hashes in Ruby
Generating cryptographic hashes in Ruby is quite easy. Ruby provides both a built in method and gives access to OpenSSL's hashing algorithms in most installations.
Eval: Running Code on the Fly
Most non-compiled languages have some kind of eval function, which will take a string and execute it as code.
Variables Declared in the Global Scope
I declared a variable in the global scope, and now I can't access it. What's going on here?
Making Digraphs in Ruby
Digraphs are extremely useful for hierarchical data visualization. However, they're not very easy to generate yourself. This is where Graphviz and the Graph gem come in.
Using the Enumerable Module
By using the Enumerable module, you can make any of your classes act like Ruby standard collections. All you need to do is implement the 'each' method.
How Can I Store Key/Value Pairs in Ruby?
Storing key/value pairs in Ruby doesn't always need to be accomplished by using a hash. You can also use the Struct and OpenStruct classes.
protect_from_forgery
A feature in Rails that protects against Cross-Site Request Forgery (CSRF) attacks.
Unit Testing with Minitest: More Assertions
MiniTest provides an array of assertion methods that will make writing tests a breeze.
Part 3: Implementing
In this part, we'll implement a complete working application.
Rails Application Flow
When you program with any framework, you relinquish flow control in favor of convenience. The following is a description of what happens to a request as it passes through Ruby on Rails.
A Quick Introduction to DataMapper
class="no-js" itemscope itemtype="http://schema.org/Article" > itemprop="description" >DataMapper is
A New Rails Project
Before you can start making models, views and controllers for your web application, you need to generate a new applications. Rails projects are too complex to create by hand, you really do need an empty project to bootstrap you. It's not hard though, there's really only one command you need to know.
The Algorithm
Before we start coding, we take some time to look at the game of 2048.
Basic Array Operations
Beyond creating arrays using literals, there are a few things you should know to get by with Arrays.
How to Install 'Git' on Windows
Installing command line tools such a Git on Windows is often difficult. Not only do you have to find a Windows port or attempt to compile the tool yourself from C source code, you also have to deal with the Windows command line. The Windows command line is, to say the least, a little lacking. Windows users are in luck here though, the MSysGit project solves both these problems.
Constants in Ruby
Like just about every programming language every conceived, Ruby supports constants. A constant is a variable whose value cannot be changed. However, in Ruby, this has some caveats.
undefined method `to_sym' for nil:NilClass
Problem: Seemingly at random, you've encountered the error undefined method `to_sym' for nil:NilClass, or a similar error message for any method name other than to_sym.
Class Variables
Class variables in Ruby are more or less as you'd expect form an object oriented language. However, Ruby throws you a curveball you can use to your advantage.
Working with Directories
Learning how to work with files is one of the first things new Ruby programmers learn. However, how to work with directories of files is something that's often skipped or only lightly touched upon. Ruby does have some powerful mechanisms for working with directories though.
Rapid Game Prototyping in Ruby
Myth: Ruby is unsuitable for game development. It's much too slow, there are no good libraries and it's too hard to deploy your games written in Ruby.
How to Display Your Ruby Version in Your Bash...
With RVM installed on your system, it's easy to have many versions of Ruby installed. And, especially if you switch between them often, it's easy to forget which Bash command prompt is using which Ruby version. You can solve this by putting your Ruby version in your Bash prompt.
Can't Modify Frozen String
I'm trying to modify a frozen string, but I keep getting this exception. Why?
Running the Ruby Profiler
Running the Ruby profiler to determine which methods are most expensive and which need to be optimized.
Hashes
Hashes are an integral part of Ruby. You will (probably) never see a non-trivial Ruby program that does not use Hashes extensively.
The Link Class
The Link class is what you use to navigate from one page to another. The Link class itself is quite small, there just isn't much to a link. It doesn't have many methods, the click method being the most used by far.
Buttons and Submitting Forms
class="no-js" itemscope itemtype="http://schema.org/Article" > itemprop="description" >Buttons primarily
Overloading Operators
What does a + b mean? That all depends on what 'a' is. Ruby allows you to define a number of arithmetic operators and they're called on the left-hand side of any such expression.
Step 1: Scaffolding Posts
Without a framework like Rails, and particularly the scaffold generator, getting up and running with any project was a pain. You'd be doing a lot of configuring and planning and typing out all the methods to create blog posts and interact with the database. Rails does all this in just a few commands, and while it's not something you'll want to deploy right away, it does give you an excellent starting point.
List of Rack Middleware
The following is a list of Rack middleware applications that come with the Rack gem. A brief description of each middleware is given.
RVM and 'sudo'
RVM is great. However, there may be times where you must run Ruby scripts with RVM as root (or another user) via sudo.
Your First Controller
Now that you have a new Rails project, you're probably at a loss of where to go. Let's start by generating a new controller.
Named Regexp Groups
Ruby 1.9 introduces the concept of a named capture group. These named groups can be defined at the beginning of a regexp statement using a trick that tells for the regexp engine to look for exactly 0 instances of the group. Later, the group can be recalled using the \g element, followed by the name of the group. You can think of named capture groups as subroutines inside of a regular expression.
Getting Information About a File in Ruby Using...
Sometimes blindly opening files just won't cut it, sometimes you need to know more information about a file before opening it.
Why JRuby?
As a Rubyist you probably know and love the official Ruby implementation. It's very stable and capable, so why should you use JRuby?
Visual Tutorial: Installing Ruby on Windows
A visual walkthrough on installing Ruby on Windows. Page 7.
Logging what Mechanize Does
class="no-js" itemscope itemtype="http://schema.org/Article" > itemprop="description" >In order to analyze
Click Blocks and Animation
Now that you know how to use the animate method , you can create a crude timer application. A timer application
Block Variable Scope in Ruby 1.9.x
The release of Ruby 1.9.1 brings new features to be learned,among them are the changes in block variable scope. Learn the new syntax for block variable scope introduced in Ruby 1.9.1.
Threads in Ruby
Ruby does have threads, however the threading support in MRI (the most widely used Ruby interpreter) is not complete.  It supports concurrency for IO-bound
How Does Ruby Compare to PHP?
What are the similarities and dissimilarities between Ruby and PHP?
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