Ariejan.net

Are you ready to dive into Rails? Want to familiarize yourself with the deeper dungeons of Ruby? Are you an aspiring game developer? Or maybe you just want to learn how to use Git or Subversion effectively?

In any case, I’ve opened up a little book shop with a hand-picked selection of books on a variety of subjects, included Ruby and Rails, Game Development (with Java) and Version Control.

Migrations have up and down methods, as we all know. But in some cases, your up method does things you can’t undo in your down method.

For example:

def self.up
  # Change the zipcode from the current :integer to a :string type.
  change_column :address, :zipcode, :string
end

Now, converting integers to strings will always work. But, you feel it coming, converting a string into an integer will not always be possible. In other words, we can’t reverse this migration.

In some very rare situations you may find yourself in the need to recompile a Debian (or Ubuntu) package. Luckily for all of use, the great Debian packaging system makes this a piece of cake.

Let’s say we want to recompile mod_python for apache 2 to hook in to python 2.5, instead of the default 2.4.