Please, Ruby devs, join() your paths

Like in most programming languages, when you write paths in ruby, e.g. to open a file you pass in a string:

filename = "bar.txt"
File.open("/home/foo/"+ filename)

This is a serious smell for several reasons. Not, as people often believe, just to cater the few Ruby developers on Windows (Windows knows how to follow “/foo/bar/” paths just as well as “\foo\bar” nowadays).

But mostly because this does not scale, gets convoluted real quick. Like so:

config_dir = "config/"
File.dirname(__FILE__) + "/../" + config_dir + "/environment.rb"
#=> ./../config//environment.rb

Ruby offers a great File.join() class method, for this. This simply uses the File::SEPARATOR to join a string.

config_dir = "config/"
File.join(File.dirname(__FILE__), "..", config_dir, "environment.rb")
#=> ./../config/environment.rb

As you may notice, double slashes are eliminated.

Also, you can inherit this behaviour from Pathname, like Rails.root does.

config_dir = "config/"
Rails.root.join(config_dir, "environment.rb")
#=> /path/to/rails/project/config/environment.rb

Rolling your own, is very beneficial, and simple too.

class MyConfig
  def dir
    Pathname.new(File.join("/", "etc", "myapp"))
  end
end

mc = MyConfig.new
mc.dir.join("templates", "example.html")
#=> "/etc/myapp/templates/example.html"

There really is no reason to fiddle with strings, concatenate slashes and whatnot, to build paths. Join is so much easier, more powerfull and above all, cleaner and more portable.