Utility Gems

RubyGems is bundled with core Ruby since 1.9, which was first released in 2007. As long as you do not run Ruby with the $ ruby --disable-gems flag, it is available to you without having to install anything. This also means that you can use some of RubyGems' support utilities for free!

1) Current Platform Info

Gem::Platform.local.os # => "linux"
Gem::Platform.local.cpu # => "x86_64"

The value is derived from RbConfig. Also see the OS gem, which provides similar functionality.

2) Gem.gzip and Gem.gunzip

Super simple access to text compression functionality:

s = "Ruby"*99
s.size #=> 396
c = Gem.gzip(s)
c.size #=> 29
Gem.gunzip(c) == s #=> true

3) Console Use Interface

If you don't feel like reinventing the wheel today, use RubyGems' neat user_interaction helpers:

require "rubygems/user_interaction"
ui = Gem::ConsoleUI.new

# Get Yes or No from the user
ui.ask_yes_no "Install, this script?", false
# ->
# Install, this script? [yN]  

# Password Prompt
password = ui.ask_for_password "Master password:"
# ->
# Master password:

# Select Option
selected = ui.choose_from_list "How to move on?", [
"Go",
"Elixir",
"EcmaScript 2016",
"Real World Haskell"
]
# ->
# How to move on?
#  1. Go
#  2. Elixir
#  3. EcmaScript 2016
#  4. Real World Haskell

4) A List of Licenses

RubyGems includes some common license identifiers:

Gem::Licenses::IDENTIFIERS # =>
["0BSD", "AAL", "ADSL", "AFL-1.1", "AFL-1.2", "AFL-2.0", "AFL-2.1", "AFL-3.0", "AGPL-1.0", "AGPL-3.0", "AMDPLPA", "AML", "AMPAS", "ANTLR-PD", "APAFML", "APL-1.0", "APSL-1.0", "APSL-1.1", "APSL-1.2", "APSL-2.0", "Abstyles", "Adobe-2006", "Adobe-Glyph", "Afmparse", "Aladdin", "Apache-1.0", "Apache-1.1", "Apache-2.0", "Artistic-1.0", "Artistic-1.0-Perl", "Artistic-1.0-cl8", "Artistic-2.0", "BSD-2-Clause", "BSD-2-Clause-FreeBSD", "BSD-2-Clause-NetBSD", "BSD-3-Clause", "BSD-3-Clause-Attribution", "BSD-3-Clause-Clear", "BSD-3-Clause-LBNL", "BSD-4-Clause", "BSD-4-Clause-UC", "BSD-Protection", "BSL-1.0", "Bahyph", "Barr", "Beerware", "BitTorrent-1.0", "BitTorrent-1.1", "Borceux", "CATOSL-1.1", "CC-BY-1.0", "CC-BY-2.0", "CC-BY-2.5", "CC-BY-3.0", "CC-BY-4.0", "CC-BY-NC-1.0", "CC-BY-NC-2.0", "CC-BY-NC-2.5", "CC-BY-NC-3.0", "CC-BY-NC-4.0", "CC-BY-NC-ND-1.0", "CC-BY-NC-ND-2.0", "CC-BY-NC-ND-2.5", "CC-BY-NC-ND-3.0", "CC-BY-NC-ND-4.0", "CC-BY-NC-SA-1.0", "CC-BY-NC-SA-2.0", "CC-BY-NC-SA-2.5", "CC-BY-NC-SA-3.0", "CC-BY-NC-SA-4.0", "CC-BY-ND-1.0", "CC-BY-ND-2.0", "CC-BY-ND-2.5", "CC-BY-ND-3.0", "CC-BY-ND-4.0", "CC-BY-SA-1.0", "CC-BY-SA-2.0", "CC-BY-SA-2.5", "CC-BY-SA-3.0", "CC-BY-SA-4.0", "CC0-1.0", "CDDL-1.0", "CDDL-1.1", "CECILL-1.0", "CECILL-1.1", "CECILL-2.0", "CECILL-2.1", "CECILL-B", "CECILL-C", "CNRI-Jython", "CNRI-Python", "CNRI-Python-GPL-Compatible", "CPAL-1.0", "CPL-1.0", "CPOL-1.02", "CUA-OPL-1.0", "Caldera", "ClArtistic", "Condor-1.1", "Crossword", "CrystalStacker", "Cube", "D-FSL-1.0", "DOC", "DSDP", "Dotseqn", "ECL-1.0", "ECL-2.0", "EFL-1.0", "EFL-2.0", "EPL-1.0", "EUDatagrid", "EUPL-1.0", "EUPL-1.1", "Entessa", "ErlPL-1.1", "Eurosym", "FSFUL", "FSFULLR", "FTL", "Fair", "Frameworx-1.0", "FreeImage", "GFDL-1.1", "GFDL-1.2", "GFDL-1.3", "GL2PS", "GPL-1.0", "GPL-2.0", "GPL-3.0", "Giftware", "Glide", "Glulxe", "HPND", "HaskellReport", "IBM-pibs", "ICU", "IJG", "IPA", "IPL-1.0", "ISC", "ImageMagick", "Imlib2", "Intel", "Intel-ACPI", "Interbase-1.0", "JSON", "JasPer-2.0", "LGPL-2.0", "LGPL-2.1", "LGPL-3.0", "LGPLLR", "LPL-1.0", "LPL-1.02", "LPPL-1.0", "LPPL-1.1", "LPPL-1.2", "LPPL-1.3a", "LPPL-1.3c", "Latex2e", "Leptonica", "Libpng", "MIT", "MIT-CMU", "MIT-advertising", "MIT-enna", "MIT-feh", "MITNFA", "MPL-1.0", "MPL-1.1", "MPL-2.0", "MPL-2.0-no-copyleft-exception", "MS-PL", "MS-RL", "MTLL", "MakeIndex", "MirOS", "Motosoto", "Multics", "Mup", "NASA-1.3", "NBPL-1.0", "NCSA", "NGPL", "NLPL", "NOSL", "NPL-1.0", "NPL-1.1", "NPOSL-3.0", "NRL", "NTP", "Naumen", "NetCDF", "Newsletr", "Nokia", "Noweb", "Nunit", "OCLC-2.0", "ODbL-1.0", "OFL-1.0", "OFL-1.1", "OGTSL", "OLDAP-1.1", "OLDAP-1.2", "OLDAP-1.3", "OLDAP-1.4", "OLDAP-2.0", "OLDAP-2.0.1", "OLDAP-2.1", "OLDAP-2.2", "OLDAP-2.2.1", "OLDAP-2.2.2", "OLDAP-2.3", "OLDAP-2.4", "OLDAP-2.5", "OLDAP-2.6", "OLDAP-2.7", "OLDAP-2.8", "OML", "OPL-1.0", "OSL-1.0", "OSL-1.1", "OSL-2.0", "OSL-2.1", "OSL-3.0", "OpenSSL", "PDDL-1.0", "PHP-3.0", "PHP-3.01", "Plexus", "PostgreSQL", "Python-2.0", "QPL-1.0", "Qhull", "RHeCos-1.1", "RPL-1.1", "RPL-1.5", "RPSL-1.0", "RSA-MD", "RSCPL", "Rdisc", "Ruby", "SAX-PD", "SCEA", "SGI-B-1.0", "SGI-B-1.1", "SGI-B-2.0", "SISSL", "SISSL-1.2", "SMLNJ", "SNIA", "SPL-1.0", "SWL", "Saxpath", "Sendmail", "SimPL-2.0", "Sleepycat", "Spencer-86", "Spencer-94", "Spencer-99", "SugarCRM-1.1.3", "TCL", "TMate", "TORQUE-1.1", "TOSL", "UPL-1.0", "Unicode-TOU", "Unlicense", "VOSTROM", "VSL-1.0", "Vim", "W3C", "W3C-19980720", "WTFPL", "Watcom-1.0", "Wsuipa", "X11", "XFree86-1.1", "XSkat", "Xerox", "Xnet", "YPL-1.0", "YPL-1.1", "ZPL-1.1", "ZPL-2.0", "ZPL-2.1", "Zed", "Zend-2.0", "Zimbra-1.3", "Zimbra-1.4", "Zlib", "bzip2-1.0.5", "bzip2-1.0.6", "diffmark", "dvipdfm", "eGenix", "gSOAP-1.3b", "gnuplot", "iMatix", "libtiff", "mpich2", "psfrag", "psutils", "xinetd", "xpp", "zlib-acknowledgement"]

The data is also accessible via a special regex:

!!Gem::Licenses::REGEXP.match?("MIT") # => true
Gem::Licenses.match? "Ruby" # => true
Gem::Licenses.match? "Crossword" # => true
Gem::Licenses.match? "Idiosyncratic" # => false

Finally, it can also assist you with finding the right license:

Gem::Licenses.suggestions "ABC" #=> ["AAL", "AML", "DOC", "ISC", "W3C"]

5) Gem::Util.silent_system

Like Kernel#system, but without printing to STDOUT/STDERR. It will temporary replace STDOUT and STDERR with a null device:

require 'rubygems/util'
# create file 123, but output nothing
Gem::Util.silent_system "touch 123"

Note: If you don't want to print anything, but you are still interested in the commands output, you can use backticks!

6) Gem::Util.traverse_parents

Get a list of parent directories of a specific directory:

require 'rubygems/util'
puts Gem::Util.traverse_parents('.').to_a

# example

/home/jan/dev/idiosyncratic/source/posts
/home/jan/dev/idiosyncratic/source
/home/jan/dev/idiosyncratic
/home/jan/dev
/home/jan
/home
/

7) Deprecation Helper

RubyGems also provides a deprecate method:

$VERBOSE = true # activate interpreter warnings

module Kernel
  extend Gem::Deprecate
  deprecate :puts, :none, 2020, 12
  deprecate :format, :sprintf, 2016, 05
end

puts "test"
# NOTE: Object#puts is deprecated with no replacement. It will be removed on or after 2020-12-01.
# Object#puts called from (irb):9.

format "%.2f", 1
# NOTE: Object#format is deprecated; use sprintf instead. It will be removed on or after 2015-05-01.
# Object#format called from (irb):13.

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