I just pushed a new version of my Diffy ruby gem.

This version does a better job when highlighting parts of lines in the html diff output.

Ward Cunningham pointed out to me that sometimes Diffy would get a little creative when finding similarities in between lines. For example, while technically correct Diffy 2.0.0 could come off as a bit of a know-it-all when it found one letter similarities between “Unescaped” and “Swallowed”.

Version 2.0.1 suppresses this creativity a little bit for clearer output:

I just released version 2.0 of Diffy.

I wanted to make it dead simple to generate attractive diff output from within a ruby application.

Here’s how you use it:

$ sudo gem install diffy
$ irb
>> string1 = <<-TXT
>" Hello how are you
>" I'm fine
>" That's great
>" TXT
=> "Hello how are you\nI'm fine\nThat's great\n" 
>> string2 = <<-TXT
>" Hello how are you?
>" I'm fine
>" That's swell
>" TXT
=> "Hello how are you?\nI'm fine\nThat's swell\n" 
>> puts Diffy::Diff.new(string1, string2)
-Hello how are you
+Hello how are you?
 I'm fine
-That's great
+That's swell

It also will generate nice html for you:

>> Diffy::Diff.new(string1, string2).to_s(:html)

You can find out more in the README

After we set up AboutUs’s search feature our (awesome) sysadmin wanted a redundant setup. He doesn’t like having to cancel his weekend if a box goes down. We talked about running an instance of HAProxy on all our app servers to load balance between two Sphinx servers, but that seemed heavy handed.

It turned out to be really easy to add this functionality to ThinkingSphinx (and the Riddle client it uses to talk to Sphinx).

At AboutUs where I work we recently re-implemented the site’s search feature. Behind the scenes the new search uses Sphinx (a super-fast and scalable search engine) and Thinking Sphinx (which allows easy configuration and querying of Sphinx from within Rails).

One thing that makes Sphinx so much faster than alternatives like Solr is that it communicates directly with your database when it is building its search index. This is far faster than talking with your application layer, and indexing the result of your application models’ methods. In our case we’re able to reindex about 40 million records in around 4 hours. Solr used to take days.

A lot of people say that Ruby is a great languages for writing Domain Specific Languages (DSLs). A DSL is a highly abstracted programming language that gives you a natural and intuitive way to deal with a specific logical domain. They can serve as easy flexible APIs for programmers or enable clients to have control over the way a system deals with their business logic. There are lots of examples of DSLs in the Ruby world. Capistrano, RSpec, Thinking Sphinx, Rails’ Routing, just to name a few.

In this post I’ll look at some of the most common ways to create a DSL in Ruby.

A DSL for Defending Medieval Castles

A new client, Medieval Guards, Inc. specializes in guarding medieval castles and fighting off Barbarian attackers.

I’m a little excited today because some code I wrote was accepted into the Ruby on Rails core.

It’s a patch I wrote to fix a tricky bug I ran into in ActiveRecord which can cause a call to one of your model’s attribute methods to sometimes throw a NoMethodError.

I came across this bug after upgrading a site I help maintain to Rails 2.3. This site allows users to download demos of software. Users have to specify which operating system they want a demo for, and this is stored in a database column named system.

One of Rails’ selling points is convention over configuration, but most apps do need some configuration. database.yml is a great example.

Here’s some code that loads data into a ruby class from a YAML config file. Just like database.yml the configuration is specific to the rails environment you’re running in.

Sometimes you want to decide whether or not to pluralize a string based on a quantity. For example, at the bottom of this article should it say 1 comment or 2 comments? It depends on how many comments we have. I was running into this in a lot while pair programming on one project, so Ian Smith-Heisters and I whipped up this simple helper which makes it easy.

class String
  def smart_pluralize(num=self)
    num.to_i.abs == 1 ? self : pluralize
  end
end