At makandra, we've built a few gems over the years. Some of these are quite popular: spreewald (> 1M downloads), active_type (> 1M downloads), and geordi (> 200k downloads)

Developing a Ruby gem is different from developing Rails applications, w...

Every time I started RubyMine, it opened the main window on the left monitor -- when moving it to the center monitor and closing it, the next time it still opened up on the left one.

Here is how I forced RubyMine to start up on a different screen...

On recent/fresh installations of Ruby 1.8.7 you may encounter this error why calling any bundled binary (or just bundle exec):

/home/arne/.rvm/gems/ruby-1.8.7-p374@global/gems/rubygems-bundler-1.4.2/lib/rubygems-bundler/noexec.rb:75:in ...

When you run rake db:rollback and nothing happens, you are probably missing the latest migration file (or have not migrated yet).

$ rake db:rollback
$ 

If that happens to you, check your migration status.

$ rake db:migrate:status

...

tl;dr: Do not use merge! for session hashes. Use update instead.

Outline

Let's assume you're modifying the Rails session. For simplicity, let's also assume your session is empty when you start (same effect when there is data):

# In o...

When using git diff, you might encounter weird characters where umlauts (or any other UTF-8) characters should be. It looks like this:

R<C3><BC>ckg<C3><A4>ngig # should be "Rückgängig"

However, not Git is to blame [but the less comma...

The way Rational#to_s works on Ruby has changed from Ruby 1.9 on. Here is how to get the old behavior back.

You may want this for things where Rationals are being used, like when subtracting Date objects from one another.

What's happening?...

While it might seem trivial to implement an invoice that sums up items and shows net, gross and vat totals, it actually involves a lot of rules and caveats. It is very easy to create invoices where numbers don't add up and a few cents are missing....

While upgrading CarrierWave from version 0.11.x to 3.x, we encountered some very nasty fails. Below are the basic changes you need to perform and some behavior you may eventually run into when upgrading your application. This aims to save you some...

iPads will not trigger click events for all elements. You can fix that, but you don't want to know why.

Example: Capturing clicks on table rows (use case would be clicking the 1st link inside it for better UI). Consider this setup:

<table>

...