Simplifying Library Requires With $LOAD_PATH
Posted by Samuel Mullen in 
When creating scripts or libraries which load custom libraries or modules in the past, I’ve generally loaded them in the following manner:
require File.join(File.dirname(__FILE__), "lib/foo")
require File.join(File.dirname(__FILE__), "lib/bar")
require File.join(File.dirname(__FILE__), "lib/baz")
This loads libraries by calling each of them with their absolute path. “File.dirname” gets the directory name for the current file (__FILE__). And “File.join” joins that directory name to “lib/xxx”.
Loading libraries in this way isn’t the DRYest way of doing things, so I was happy when I ran across this in the Watchr source code:
$LOAD_PATH.unshift(File.dirname(__FILE__))
$LOAD_PATH is a global array variable holding all the paths from which ruby loads libraries. Ruby searches for libraries proceeding from the path in element 0 to the path in the last element until it finds the requested library.
The above snippet of code from Watchr places the current path at the front of the load path (unshift). Now, all following “require”s will look there first and then proceed normally through the standard paths.
So now, rather than specifically calling each library with an absolute path, I can use the following:
$LOAD_PATH.unshift(File.dirname(__FILE__))
require ‘foo’
require ‘bar’
require ‘baz’
