#![desc = "Random thoughts of a software engineer"]

Automatic versioning in Xcode with git-describe

Do you manually set a new version number in Xcode every time you release a new version of your app? Or do you use some tool that updates the Info.plist in your project like agvtool or PlistBuddy? Either way, you probably know that it's a pain to keep track of the version number in the project.

I recently spent some time trying out various methods to automatically get the version number from git and put it into the app that Xcode builds. I found that most of them have drawbacks, but in the end I found a way that I finally like most. Here's how.


IPv6 in Docker containers

Docker is great. It's a client-server based tool that makes it easy to run something in isolated Linux containers (LXC). Linux containers usually need some non-trivial configuration to be set up and run. Docker helps with this by providing easy methods to build container images and ready to run LXC configurations for running them. Unfortunately, it ignores IPv6... 


Google Charts on your site, the unobtrusive way

For a recent project, I needed to visualize some simple backend database statistics to admin users. Nothing exciting, just some simple numbers like count of subscriptions and purchases per day and such. When I started to work on some simple stats calculations, I already had in mind that I want to display the result in nice charts rather than in boring tables with numbers. And I wanted nice, interactive HTML 5 charts that display with almost no load time and fetch their data to display with Ajax.

There are several libraries that offer you to display charts in various ways like generating images to display or embedding Flash objects (yieks) into your page. Nowadays you surely want to use a library that displays interactive charts using Javascript and HTML5 though. In Railscast #223, there's a nice tutorial how to use a few libraries.

However, I ended up using Google's free chart service Google Charts, paired with unobtrusive Javascript using jQuery. Here's how I did it:


Rails I18N core translation updater and CSS naked plugin as gems

It has been quite a while that I created these two Rails plugins, but they still serve their purpose without problems even in newer applications. Since Rails plugins as a gem are much easier to maintain, I took some time to move these two plugins to gems. This makes them even more easy to use and especially more maintainable.

I'm talking about rails-i18n-updater, a plugin that merges and manages Rails core translations in your application — a helper that I don't want to miss in any i18n-enabled application anymore. And css_naked, a simple plugin that disables all stylesheets during the CSS naked day event once a year.

Both plugins are ready for Rails 3 and work well with Ruby 1.9, btw.


A Rails plugin to use core translations

If you're writing an i18n-enabled Rails application, you have to deal with the translation of your own application as well as with the translation of several Rails core strings (like validation error messages, date formats, and so on). You usually don't need to translate the Rails core strings yourself, since there's a big repository of user-contributed core translations you can pull into your application. However keeping this translations up to date in your application can quickly become cumbersome.

For this reason, I refactored the rails-i18n repository a while ago and made it a Rails plugin. You could install the plugin to your application and it provided Rails core translations for you. Unfortunately it became annoying to keep the fork up to date with the latest translation changes since every rebase or merge was a pain because of the moved file locations.

So my latest solution is another small plugin called rails-i18n-updater, which does not contain the translations itself but downloads them from the above mentioned repository of core translations.


Ruby 1.9 and file encodings

Just out of curiosity, I took two of my recent Rails applications today and tried them with Ruby 1.9. It was surprisingly easy to make all tests pass without any warnings or errors. Rails 2.3 already has quite good support for Ruby 1.9. The main gotcha however was about file encodings. If you have source files which contain non-ASCII characters, Ruby 1.9 now needs to know which encoding the file was saved with. If you don't specify the encoding for a file with non-ASCII characters, you'll get an invalid multibyte char (US-ASCII) error message.


Routing parameters with a dot

Last week I received an interesting bug report for an application I'm working on at the office. It has a controller with an index action that displays a list of items which can be filtered by tags. A tester reported that every time he chooses to filter the list by a tag that contains a dot, the site returns an error. First this seems strange since tags with a dot worked perfectly fine in tests.

But after digging deeper, I found a surprising reason for this strange error: To make URLs look nicer, I defined an extra route like this:


Testing Cookies in Rails 2.3

While moving some applications to Rails 2.3 recently, I stumbled across some problems with testing cookies. E.g. this blog uses cookies to remember your name, email address and web url if you leave a comment. This way, you don't need to re-enter these information the next time you leave a comment. These cookies are set by the controller action that creates new comments (in CommentsController#create):


CSS Naked Day 2009: a Rails plugin

On April 9th 2009, the fourth CSS Naked Day event will take place. The idea behind this event is to promote web standards (like proper semantic markup and a good hierarchy structure). On April 9th, participants are encouraged to completely remove all stylesheets from their site, stripping it entirely of its design. If your site has proper semantic markup, it'll stay well usable and understandable even without styles. If not, you better hide and don't take part in this event :)

To make it as easy as possible, I created a little Rails plugin that, once installed to an app, simply disables the stylesheet_link_tag helper for the duration of the event. It's as easy as install and forget (assuming that you used stylesheet_link_tag in your layouts and didn't add inline styles or stylesheet links manually).

So let's see how many sites will join this funny but yet expressive event this year. It's time to show off your <body> ;-)


Let browsers cache static files to greatly speed up your site

There are many factors that determine how long a page takes to show up in a browser. When a page is requested by a browser, the server needs some time to compute the page contents (controller, model/database, view) and returns HTML to the browser. Besides network latency and throughput (which can be optimized by choosing a good hosting provider), there are several ways to speed up the page generation itself (like memoization, action/fragment/query-caching, using memcached, and so on).

But even after the HTML page itself has been transferred to the browser, the page is not necessarily ready to display yet. A page usually references more resources like stylesheets, javascripts and images that need to be requested and transferred. These are mostly static files (located in the public folder of a Rails application) and are directly served by the webserver without invoking the Rails application. So these files takes very little computation time on the server, but they still need some time and bandwith to transfer, which can be optimized.