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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 Forming Command Line Arguments...
Use command-line arguments to pass parameters to your Ruby scripts from the command line.
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.
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 Using Environmental Variables...
Using environment variables in Ruby.
Using the 'split' Method in Ruby
String manipulation using the split method in Ruby. Split strings into a list of substrings.
How to Use Comments for Ruby Code
Use comments to annotate your Ruby code.
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.
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.
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.
A Quick Guide to Installing Ruby on Linux
How to install Ruby on the Linux operating system.
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.
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.
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 Strings
Using and manipulating strings and substrings in Ruby. Page 4.
Here's What Ruby Is
What type of language is the Ruby programming language?
How to Use String Substitution in Ruby
class="no-js" itemscope itemtype="http://schema.org/Article" > itemprop="description" >Splitting a string
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?
Checking Your Email with Ruby
How to check POP3 email accounts in Ruby.
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.
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').
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?
Using the Logger Library--How to Write Log...
How to use the logger library to create and write to log files in Ruby.
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.
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.
How to Use 'Ternary' (Conditional) Operators in...
class="no-js" itemscope itemtype="http://schema.org/Article" > itemprop="description" >The ternary (or
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.
Instantiation and the Initialize Method
Ruby objects are instantiated using the Class.new method, and initialize using their own initialize methods.
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.
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.
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.
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.
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.
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.
Installing RVM on Linux
Installing the Ruby Version Manager (RVM) on Linux. Page 2.
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.
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.
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.
Can I add empty directories to Git repositories?
Can I add empty directories to Git repositories?
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.
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.
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?
Block Parameters and Yielding
class="no-js" itemscope itemtype="http://schema.org/Article" > itemprop="description" >Block parameters
Optional Method Parameters with Hashes
Using hashes to simulate optional named parameters in methods.
How to Install Ruby
How to install the Ruby interpreter on Windows, Linux and OS X.
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.
Getting Started with Bundler
The basics of using Bundler are very trivial, you can be up and running in just a few minutes.
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.
Understanding 'String Literals' in Ruby
The basics of strings, string interpolation, single and double quotes, escape sequences and alternate string literal syntaxes. Page 2.
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.
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.
How Does Ruby Compare to Python?
How do Ruby and Python compare in terms of features, form and function?
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.
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.
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?
Part 3: Implementing
In this part, we'll implement a complete working application.
4 Ways Ruby is Better Than Your Programming...
A comparison of Ruby to other programming languages, including Perl, Java, Python and PHP.
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.
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.
Global Variables
Global variables are not often used in Ruby, however, you should at least understand their usage should you ever encounter them.
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.
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.
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. Page 5.
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.
Install Ruby on Windows
How to install the Ruby interpreter on the Windows operating system.
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
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.
Sorting Arrays
One of the most common tasks when dealing with arrays is to sort them. Luckily, Ruby makes this simple and flexible.
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.
Hello, Sinatra! Using Sinatra in Ruby
How to get started in Sinatra, including how to use actions, parameters, ERB and views.
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.
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!
The Algorithm
Before we start coding, we take some time to look at the game of 2048.
Using Rack
In the previous article, you learned what Rack is. Now, it’s time to start using Rack and serve up some pages.
Constant Variables
class="no-js" itemscope itemtype="http://schema.org/Article" > itemprop="description" >The speed of light
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.
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.
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.
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.
How to Use and Create Blocks in Ruby
How to use blocks in Ruby.
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?
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.
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.
How to Install Gems from Git Repositories in Ruby
How to install gems from git repositories.
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.
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.
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.
Quickly Run an HTTP Server with Ruby (Also, the...
Quickly Run an HTTP Server with Ruby (Also, the Un Library)
Installing jRuby With RVM on OS X
As with most flavors of Ruby, the easiest, cleanest and least painful way to install jRuby is with RVM, the Ruby Version Manager. And although jRuby is different than MRI, the official Ruby interpreter, it can be installed just as easily, arguably easier. Page 3.
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.
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.
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.
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.
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.
What's New in Rails 4?
Now that Rails 4 is out, let's see what's new.
Buttons and Submitting Forms
class="no-js" itemscope itemtype="http://schema.org/Article" > itemprop="description" >Buttons primarily
Is Ruby a Good First Language to Learn?
Is Ruby a good first language to learn? Everyone has to start somewhere, and is Ruby an appropriate place to start if you're looking to take the plunge and learn a programming language?
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?
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.
Sinatra URL Matching
How do do various types of URL matching in Sinatra.
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.
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?
Mutexes in Ruby
Mutexes are a way to prevent more than one thread from accessing the same resource (variable, file, socket, etc) at the same time.
What is Bundler?
Bundler is a gem dependency manager for Ruby.
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.
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.
Using RVM Gemsets
One of the most powerful, useful and often overlooked features of RVM is the gemset. A gemset is a separate gem directory, so the gems in one gemset don't conflict with the gems in another gemset.
Finding Links
class="no-js" itemscope itemtype="http://schema.org/Article" > itemprop="description" >Most likely, you'll
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.
An Introduction to Distributed Ruby
Distributed Ruby, or DRb, is a library that allows you to communicate with remote Ruby objects and programs, using TCP/IP network protocols.
Worked Example: Tabular Data
Much is made of the two base data structures in Ruby: the Array and the Hash. However, it's also quite easy to use two dimensional arrays in Ruby.
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.
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.
Dynamic Method Calls
If you're coming from a compiled language, it's easy to think that method calls are like native function calls. This is simply not the case in Ruby.
Dealing With Vulnerabilities: Pay Attention to...
Enabling forgery protection is only one way to counteract security vulnerabilities in your Ruby code. You also need to pay attention to idempotence, or the ability to keep a value unchanged.
One Tree to Rule Them All
Some problems seem difficult, there are just too many things to consider and it's going to become a mess. However, if you analyze it, there's often a single data structure that will make the whole thing easier.
Installing Ruby on Rails on OS X
While Apple does include both Ruby and Ruby on Rails by default with OS X, you'll need to install newer versions. This is a bit of a process, but thankfully you'll only need to get through this just once.
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.
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.
Practical Ruby Projects: Ideas for the Eclectic...
A review of the book Practical Ruby Projects: Ideas for the Eclectic Programmer by Topher Cyll from Apress.
Quick Tip: Last Result in IRB
There's a really quick way to get the result of the last expression evaluated in IRB.
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.
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.
Making Forms and Views
So far, we've discussed how to use Sinatra in general, how to handle and route requests, and how to build views using Haml. Before we take the plunge into using data storage with Sinatra, let's put what we've discussed so far into practice. This article explains how to use Sinatra to provide a web interface for a gem. Page 4.
3 Ruby Scripts for Twitter Automation
Exploring and knowing the Twitter API is fine, but what do you do from there? Here are 3 practical scripts to help you follow followers on Twitter, update your Twitter account via an RSS feed and to be notified of your friend's new Tweets as they come in.
Using Haml with Sinatra
How to use Haml to create Sinatra views and layouts. Page 7.
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.
Running the Ruby Profiler
Running the Ruby profiler to determine which methods are most expensive and which need to be optimized.
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.
Hash Tips and Tricks
Hashes aren't just data structures, they have a few tricks up their sleeves. And while you may never end up using any of these tricks, they really show off how flexible the Hash class 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.
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.
Visual Tutorial: Installing Rubygame on Windows
A visual tutorial with screenshots showing how to install the Rubygame library on Windows, including installing all needed DLL files. Page 4.
Exceptions
Exceptions are used to handle things the unexpected things that might go wrong with your Ruby code. This article addresses what Exceptions are and how they can be used.
Using Temporary Files
There are many hidden pitfalls when using temporary files. Ruby's Tempfile class solves many of these.
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 ActiveRecord?
What is ActiveRecord? What can you do with it?
Agile Development
The principles of Agile Development and how agile applies to Ruby on Rails.
Cloning 2048 in Ruby
In this series of articles, a complete clone of the game 2048 is written from scratch.
Logging what Mechanize Does
class="no-js" itemscope itemtype="http://schema.org/Article" > itemprop="description" >In order to analyze
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.
Can't Modify Frozen String
I'm trying to modify a frozen string, but I keep getting this exception. Why?
Check Email With Ruby
Learn to use Ruby's pre-installed POP3 libraries to check your email.
First Step to a Development Environment
The first step to a Ruby development environment on Linux? Install Ruby, of course! Page 5.
Creating a "Hello World" Program With WxRuby
To get started in WxRuby, first look at this "Hello world" program. It's a simple program that displays
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.
Worked Example: Number Guessing Game
A number guessing game is written, and each of its features explored.
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