I was recently updating an example Rails 3 app to Rails 4, and was curious what had changed in terms of the default files and directories. There’s always at least one small tweak to an environment file that I’m afraid I’ll miss. To spot the differences, I generally use a command-line tool. But being a visual person, I’ve always wanted a way to see side-by-side differences and merge individual changes.

Coincidentally, last week the good folks at Black Pixel released Kaleidoscope 2: a file comparison app for Mac. I know some of their crew, but I honestly had no idea what they were working on. So it was serendipitous when they sent me an evaluation copy. Anyway, after giving it a quick whirl I knew I had found what I’ve always been looking for when updating Rails apps.

Here’s a quick screencast demonstrating how I’ve been using Kaleidoscope. I drop a stock Rails 4 app directory on the left and a Rails 3 app directory on the right, and then copy changes from left to right:

I just love seeing the highlighted differences and being able to copy a change from one app to the other with a quick keystroke. It’s wicked fast and beautifully designed!

If you’re a visually-oriented Mac user who routinely does file and directory comparisons, give Kaleidoscope a try. You can kick the tires during the 15-day trial and if you love it as much as I do it’s on sale for 50% off through the end of the month.