Ruby articles

Nested errors in Ruby with Exception#cause

It's a common pattern in Ruby to rescue and exception and re-raise another kind of exception. But the original exception isn't lost! You can use Exception#cause to grab it. In this post we show you how.

How to "try again" when exceptions happen in Ruby

Ruby provides a few interesting mechanisms that make it easy to "try again" - though not all of them are obvious or well-known. In this post we'll take a look at these mechanisms and how they work.

Using TracePoint to explore complex exception behavior in Ruby

Ever wanted to know which method caused an exception - even if the exception was swallowed before you could get your hands on it? You can do all this and more with the magic of TracePoint.

How to change the process name of your Ruby script as shown by `top` and `ps`

It's super handy to be able to refer to processes by name. But default process names can be pretty cryptic. This post will show you how to set friendly process names, and even how to use the process name to provide status summaries for long running processes like Unicorn.

The clever hack that makes `items.map(&:name)` work

The &: trick is a great shortcut when using enumerable methods like map. The way it works may surprise you. In this post we'll look in detail at exactly how code like users.map(&:name) functions under the hood.

Advanced Ruby Hash techniques

When you use something as much as Ruby developers use Hashes, it's easy to think you've seen it all.

But I'm here to tell you that the humble ruby Hash has a few tricks up its sleeve. Far from being a dumb key-value system, the Hash object gives you...

How to dump a Rails model to a YAML File

I've been wanting to do some work for a while on the UI for our performance monitoring system. But the way the performance monitoring system works, it's difficult to create fake data for development.

The solution? Jump into a Rails console on our...

Let's build an RSS to email digest script with Ruby

I needed a script that will fetch our most recent blog posts and output a "digest" HTML email that I can personalize. In this post we walk through the process of creating it. You'll learn about fetching and parsing RSS as well as templating with ERB. Yes! You can use ERB outside of Rails!

How OpenStruct can kill performance

An OpenStruct is around 10x slower to initialize than a Struct. That was the surprising result of this benchmark where we pitted structs vs classes vs hashes vs OpenStruct. Hashes didn't do much better.

Bitwise hacks in Ruby

If you've ever thought of using Ruby to access libraries in C or Java, or to manipulate the operating system then it's critical that you know the basics of bit manipulation. We start out with the basics of binary in Ruby and finish with John Carmack's legendary inverse square root approximation.

Profile your gem memory usage with Derailed

Is your Rails app is taking up a lot of RAM? Perhaps your application’s memory footprint is being enlarged by one or more bloated gems. The Derailed gem provides some awesome tools for detecting gem bloat.

Understanding the rails-jquery CSRF vulnerability (CVE-2015-1840)

Several new security disclosures were released recently. One of them was for rails-jquery, the javascript library that implements "remote" links and forms in Rails. In this post we'll dissect the problem and see how it was fixed.

Using Lambdas in Ruby

Did you know you can use lambdas as a kind of dynamic hash replacement? The truth is, lambdas are pretty cool once you start to investigate them. In this post we'll cover basic usage and then show you some cool lambda tricks.

Securing environment variables

In a previous post we showed you how the environment variable system works, and busted some common myths. But as one helpful reader pointed out, we didn't say much about security. Since it's become common to use env vars for storing secret API keys and other valuable information, It's important to understand the security implications. Let's take a look.

The Rubyist's guide to environment variables

If you want to be able to effectively manage web apps in development and in production, you have to understand environment variables. This post will show you how environment variables really work - and perhaps more importantly, how they DON'T work. We'll also explore some of the most common ways to manage environment variables in your Rails apps.

Working with exceptions in Pry

By now I think everyone agrees that Pry is the best thing to happen to the Rails console since...well, ever. Built-in to pry are a few really cool features that make it much easier to work with exceptions than it was in plain old IRB. Let's take a look.

Understanding the Ruby exception hierarchy

In this post we look at Ruby's exception class heirarchy, and how you can use it to be as broad or as narrow as you like when rescuing exceptions.

Custom exceptions in Ruby

Exceptions are classes, just like everything else in Ruby. This post will show you how to create your own custom exceptions without falling into some common traps that snare beginners.

Capturing stdout & stderr from shell commands via Ruby

tl;dr If you want to run a shell command from Ruby and capture its stdout, stderr and return status, check out the Open3.capture3 method. If you'd like to process stdout and stderr data in a streaming fashion, check out Open3.popen3.

So many bad choices

Ruby's Exception vs StandardError: What's the difference?

Never rescue Exception in Ruby! - Maybe you've heard this before. It's good advice, but it's pretty confusing unless you're already in the know. Let's break this statement down and see what it means.