Cryptic Ruby Global Variables and Their Meanings

Posted Almost 11 years ago. Visible to the public. Linked content.

The linked page lists and explains global Ruby "dollar" variables, such as:

$: (load path)
$* (ARGV)
$? (Last exit status)
$$ (PID)
$~ (MatchData from last successful match)
...and many more you'll need when reading weird code.

Regex

$~ (last MatchData)
$1 $2 $3 $4 (match groups from the last pattern match)
$& (last matched string)
$+ (last match group)
`$`` (the string before the last match)
$' (the string after the last match

See this extensive list of variables Show archive.org snapshot .

UI/UX Design by

We make sure that your target audience has the best possible experience with your digital product. You get:

Design tailored to your audience
Proven processes customized to your needs
An expert team of experienced designers

Related cards:

Missing certificates for rubygems and bundler in Ruby 1.8.7

Using Ruby 1.8.7 you will not be able to use the maximum versions Rubygems 1.8.30 and Bundler 1.17.3 with https://rubygems.org/ anymore. This is a result of a server certificate on December 5th, 2020. The resulting errors will...

Ruby: Referencing global variables with the built-in English library

tl;dr

Don't forget require 'English' if you use a named global such as $LAST_MATCH_INFO. Otherwise this could result in an annoying bug.

With Ruby's build-in library English y...

Ruby: How to use global variables for a conditional debugger

You can share a state in Ruby with global variables. Even if you should avoid them whenever possible, for debugging an application this could be temporary quite handy.

Exa...

Objective-C for Rubyists | PeepCode Screencasts for Web Developers and Alpha Geeks

If you know Ruby and you want to write applications for Mac OS X or the iPhone, you’re in a great place to start! This concise and content-packed 80-minute screencast will teach you what you need to know to start programming in Objective-C.

Global variables in Ruby

List of global variables available to a Ruby script.

The many gotchas of Ruby class variables

TLDR: Ruby class variables (@@foo) are dangerous in many ways. You should avoid them at all cost. See bottom of this card for alternatives.

Class variables are shared between a class hierarchy
---------------------------------------------------...

Ruby and Rails deprecation warnings and how to fix them

Add deprecation warnings and their solution or link to available solutions.

Global access to Rake DSL methods is deprecated. Please include Rake::DSL into classes and modules which use the Rake DSL methods.
---------------------------------------...

RubyMine: Set specific Ruby version per project

If your project uses another version than your default Ruby, RubyMine will give you incorrect inspections, for example.\
Here is how to switch which Ruby you use in RubyMine.

File → Settings (Or press Ctrl+Alt+S)
Select "Ruby SDK and Gem...

RubyMine: Find and Replace with Regex (Capture Groups and Backreferences)

tl;dr

In RubyMine you can use find and replace with capture groups (.*?) and backreferences $1 (if you have several groups: $[Capture-Group ID]).
Named captures (?<text>.*) are also supported.

Examples

Replace d...

Ruby: A small summary of what return, break and next means for blocks

Summary

Use return to return from a method. return accepts a value that will be the return value of the method call.
Use break to quit from a block and from the method that yielded to the block. break accepts a value that suppl...

Posted by Arne Hartherz to makandra dev (2013-07-17 10:19)