What does $:.push do in ruby?

Question

I found this in Gemspec file of surveyor gem. What does the following line do?

$:.push File.expand_path("../lib", __FILE__)
require "surveyor/version"

Why does the $:.push thing do? To me it looks like its just requires the ../lib/surveyor/version file. if so, can't I just replace that with following one line?

require File.expand_path('../lib/surveyor/version', __FILE__)

Are both these same thing? If not, then what the difference?

Fayfayal

Just a side note: $LOAD_PATH << File.expand_path ... does the same and looks a bit less obfuscated, IMHO. – Gnathion

indeed, thanks for the tip :) – Fayfayal

Symbolhound.com is useful for searching syntax like this. – Acropetal

Answer 1

$: is Ruby's load path, so it's in fact adding the a subfolder /lib of a folder in which __FILE__ resides to this array, so that other files from this gem can be required.

Denaedenarius

Basically a shortcut of having to write the complete path. That explains it. Thanks! – Fayfayal

@Gaurish: Not only that. The gem can assume that it is in the load path, in which it will fail to load if you require it by full path, without adding it to the load path. – Gnathion