Posts Tagged ‘require’

require

Monday, January 14th, 2008

Here are some different ways to require stuff in ruby. The funny ones courtesy of why the lucky stiff.

require "rubygems"
require "open-uri"
require "yaml"
[ "rubygems", "open-uri", "yaml" ].each { |s| require s }
%w[rubygems open-uri yaml].map(&method(:require))

File.dirname(__FILE__)

What got me looking at require was how annoying it is to use the File.dirname(__FILE__) syntax all the time in init.rb’s, like:

require File.dirname(__FILE__) + "/parser/black_cat"
require File.dirname(__FILE__) + "/parser/dar"
require File.dirname(__FILE__) + "/parser/dc_nine"
require File.dirname(__FILE__) + "/parser/iota"
require File.dirname(__FILE__) + "/parser/jammin_java"

I am always just verbose with requires, I don’t know why. It gets even less readable if you start using File.join(...). I was poking around in the rails source to see how they do requires and they use $::

$:.unshift(File.dirname(__FILE__)) unless
  $:.include?(File.dirname(__FILE__)) || $:.include?(File.expand_path(File.dirname(__FILE__)))
 
require 'action_controller/base'
require 'action_controller/request'
require 'action_controller/rescue'
...

$:

What is $:?

irb(main):001:0> $:
=> ["/usr/local/lib/ruby/site_ruby/1.8", "/usr/local/lib/ruby/site_ruby/universal-darwin8.0", 
"/usr/local/lib/ruby/site_ruby/1.8/universal-darwin8.0", "/usr/local/lib/ruby/site_ruby", 
"/usr/local/lib/ruby/1.8", "/usr/local/lib/ruby/1.8/universal-darwin8.0", 
"/usr/local/lib/ruby/1.8/universal-darwin8.0", "."]

Its the load path. It turns out $LOAD_PATH is a synonym. So that would take me:

$LOAD_PATH.unshift(File.dirname(__FILE__))
 
require "parser/black_cat"
require "parser/dar"
require "parser/dc_nine"
require "parser/iota"
require "parser/jammin_java"

But is this a bad idea? What if the load path gets large? Do we care?

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