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By David Heinemeier Hansson on April 29, 2014 "Code that's hard to test in isolation is poorly designed", goes a common TDD maxim. Isolation meaning free of dependent context and separated from collaborators, especially "slow" ones like database or file IO. The prevalent definition of "unit" in unit testing (though not everyone agrees with this). This is some times true. Some times finding it diff

By David Heinemeier Hansson on April 23, 2014 Test-first fundamentalism is like abstinence-only sex ed: An unrealistic, ineffective morality campaign for self-loathing and shaming. It didn't start out like that. When I first discovered TDD, it was like a courteous invitation to a better world of writing software. A mind hack to get you going with the practice of testing where no testing had happen

By David Heinemeier Hansson on Jan 6, 2013 In languages less open than Ruby, hard-coded class references can make testing tough. If your Java code has Date date = new Date(); buried in its guts, how do you set it to a known value you can then compare against in your tests? Well, you don't. So what you do instead is pass in the date as part of the parameters to your method. You inject the dependenc

By David Heinemeier Hansson on Dec 27, 2012 There are lots of à la carte software environments in this world. Places where in order to eat, you must first carefully look over the menu of options to order exactly what you want. I want this for my ORM, I want that for my template language, and let's finish it off with this routing library. Of course, you're going to have to know what you want, and y

By David Heinemeier Hansson on Dec 24, 2012 My appearance on the Ruby Rogues podcast recently came up for discussion again on the private Parley mailing list. A long list of topics were raised and I took a time to ramble at large about all of them at once. Apologies for not taking the time to be more succinct, but at least each topic has a header so you can skip stuff you don't care about. Maintai

By David Heinemeier Hansson on November 9, 2009 ActionMailers has to deal with a bit of a split personality. On the one hand, their organization and flow structure is very much akin to controllers. They have multiple methods that all correspond to actions. They render views from templates. They can even have layouts. On the other hand, Rails by default puts them in app/models. Looking at these two

By David Heinemeier Hansson on November 14, 2008 There are lots of great JavaScript libraries out there. Prototype is one of the best and it ships along Rails as the default choice for adding Ajax to your application. Does that mean you have to use Prototype if you prefer something else? Absolutely not! Does it mean that it's hard to use something else than Prototype? No way! It's incredibly easy

By David Heinemeier Hansson on November 13, 2008 Ruby on Rails has been around for more than five years. It's only natural that the public perception of what Rails is today is going to include bits and pieces from it's own long history of how things used to be. Many things are not how they used to be. And plenty of things are, but got spun in a way to seem like they're not by people who had either

By David Heinemeier Hansson on April 3, 2008 I've been writing a little bit of PHP again today. That platform has really received an unfair reputation. For the small things I've been used it for lately, it's absolutely perfect. I love the fact that it's all just self-contained. That the language includes so many helpful functions in the box. And that it managed to get distributed with just about e

By David Heinemeier Hansson on January 9, 2008 Most Rails contributors are not big users of shared hosting and they tend to work on problems or enhancements that'll benefit their own usage of the framework. You don't have to have a degree in formal logic to deduce that work to improve life on shared hosting is not exactly a top priority for these people, myself included. That's not a value judgeme

I've said it before, but it bears repeating: There's nothing interesting about how Ruby on Rails scales. We've gone the easy route and merely followed what makes Yahoo!, LiveJournal, and other high-profile LAMP stacks scale high and mighty. Take state out of the application servers and push it to database/memcached/shared network drive (that's the whole Shared Nothing thang). Use load balancers be

I write regularly on HEY World and speak on The REWORK Podcast. You can also find me on X, LinkedIn, Instagram, and YouTube. Or send me an email to dhh@hey.com. Creator of Ruby on Rails Hundreds of thousands of programmers around the world have built amazing applications using Ruby on Rails. The open-source web framework that I created in 2003, and continue to develop to this day. Some of the more