Skip to content

Commit

Permalink
Overhaul rubygems-basics (2022)
Browse files Browse the repository at this point in the history 
Signed-off-by: Takuya Noguchi <[email protected]>
  • Loading branch information
@tnir
tnir committed Jun 26, 2022
1 parent 31ff160 commit f17091c
Showing 1 changed file with 83 additions and 60 deletions.
143 changes: 83 additions & 60 deletions rubygems-basics.md
View file
Original file line number Diff line number Diff line change
Expand Up @@ -11,8 +11,7 @@ next: /what-is-a-gem
The `gem` command allows you to interact with RubyGems.

Ruby 1.9 and newer ships with RubyGems built-in but you may need to upgrade for
bug fixes or new features. To upgrade RubyGems or install it for the first
time (if you need to use Ruby 1.9) visit the
bug fixes or new features. To upgrade RubyGems, visit the
[download](https://rubygems.org/pages/download) page.

If you want to see how to require files from a gem, skip ahead to [What is a
Expand All @@ -37,11 +36,11 @@ expression characters in your query:

*** REMOTE GEMS ***

rails (4.0.0)
rails (7.0.3)
rails-3-settings (0.1.1)
rails-acm (0.1.0)
rails-action-args (0.1.1)
rails-admin (0.0.0)
rails-ajax (0.2.0.20130731)
rails-action-authorization (1.1.2)
[...]

If you see a gem you want more information on you can add the details option.
Expand All @@ -52,9 +51,9 @@ with details requires downloading more files:

*** REMOTE GEMS ***

rails (4.0.0)
rails (7.0.3)
Author: David Heinemeier Hansson
Homepage: http://www.rubyonrails.org
Homepage: https://rubyonrails.org

Full-stack web application framework.

Expand All @@ -68,23 +67,23 @@ The `install` command downloads and installs the gem and any necessary
dependencies then builds documentation for the installed gems.

$ gem install drip
Fetching: rbtree-0.4.1.gem (100%)
Building native extensions. This could take a while...
Successfully installed rbtree-0.4.1
Fetching: drip-0.0.2.gem (100%)
Successfully installed drip-0.0.2
Parsing documentation for rbtree-0.4.1
Installing ri documentation for rbtree-0.4.1
Parsing documentation for drip-0.0.2
Installing ri documentation for drip-0.0.2
Fetching drip-0.1.1.gem
Fetching rbtree-0.4.5.gem
Building native extensions. This could take a while...
Successfully installed rbtree-0.4.5
Successfully installed drip-0.1.1
Parsing documentation for rbtree-0.4.5
Installing ri documentation for rbtree-0.4.5
Parsing documentation for drip-0.1.1
Installing ri documentation for drip-0.1.1
Done installing documentation for rbtree, drip after 0 seconds
2 gems installed

Here the drip command depends upon the rbtree gem which has an extension. Ruby
installs the dependency rbtree and builds its extension, installs the drip gem,
then builds documentation for the installed gems.

You can disable documentation generation using the `--no-doc` argument when
You can disable documentation generation using the `--no-document` argument when
installing gems.

Requiring code
Expand All @@ -93,31 +92,47 @@ Requiring code
RubyGems modifies your Ruby load path, which controls how your Ruby code is
found by the `require` statement. When you `require` a gem, really you're just
placing that gem's `lib` directory onto your `$LOAD_PATH`. Let's try this out
in `irb` and get some help from the `pretty_print` library included with Ruby.
in `irb`.

*Tip: Passing `-r` to
`irb` will automatically require a library when irb is loaded.*

% irb -rpp
>> pp $LOAD_PATH
[".../lib/ruby/site_ruby/1.9.1",
% irb
irb(main):001:0> pp $LOAD_PATH
[".../lib/ruby/site_ruby/3.1.0",
".../lib/ruby/site_ruby/3.1.0/x86_64-linux",
".../lib/ruby/site_ruby",
".../lib/ruby/vendor_ruby/1.9.1",
".../lib/ruby/vendor_ruby/3.1.0",
".../lib/ruby/vendor_ruby/3.1.0/x86_64-linux",
".../lib/ruby/vendor_ruby",
".../lib/ruby/1.9.1",
"."]
".../lib/ruby/3.1.0",
".../lib/ruby/3.1.0/x86_64-linux"]

By default you have just a few system directories on the load path and the Ruby
standard libraries. To add the awesome_print directories to the load path,
you can require one of its files:

% irb -rpp
>> require 'ap'
$ gem install awesome_print
[...]
$ irb
irb(main):001:0> require "ap"
=> true
>> pp $LOAD_PATH.first
".../gems/awesome_print-1.0.2/lib"

Note: For Ruby 1.8 you must `require 'rubygems'` before requiring any gems.
irb(main):002:0> pp $LOAD_PATH.first
".../gems/awesome_print-1.9.2/lib"

*Tip: Passing `-r` to `irb` will automatically require a library when irb is
loaded.*

$ irb -rap
irb(main):001:0> ap $LOAD_PATH
[
[0] ".../bundle/gems/awesome_print-1.9.2/lib",
[1] ".../lib/ruby/site_ruby/3.1.0",
[2] ".../lib/ruby/site_ruby/3.1.0/x86_64-linux",
[3] ".../lib/ruby/site_ruby",
[4] ".../lib/ruby/vendor_ruby/3.1.0",
[5] ".../lib/ruby/vendor_ruby/3.1.0/x86_64-linux",
[6] ".../lib/ruby/vendor_ruby",
[7] ".../lib/ruby/3.1.0",
[8] ".../lib/ruby/3.1.0/x86_64-linux"
]

Once you've required `ap`, RubyGems automatically places its
`lib` directory on the `$LOAD_PATH`.
Expand Down Expand Up @@ -150,36 +165,45 @@ The `list` command shows your locally installed gems:

*** LOCAL GEMS ***

bigdecimal (1.2.0)
drip (0.0.2)
io-console (0.4.2)
json (1.7.7)
minitest (4.3.2)
psych (2.0.0)
rake (0.9.6)
rbtree (0.4.1)
rdoc (4.0.0)
test-unit (2.0.0.0)
abbrev (default: 0.1.0)
awesome_print (1.9.2)
base64 (default: 0.1.1)
benchmark (default: 0.2.0)
bigdecimal (default: 3.1.1)
bundler (default: 2.3.7)
cgi (default: 0.3.1)
csv (default: 3.2.2)
date (default: 3.2.2)
debug (1.4.0)
delegate (default: 0.2.0)
did_you_mean (default: 1.6.1)
digest (default: 3.1.0)
drb (default: 2.1.0)
drip (0.1.1)
english (default: 0.7.1)
[...]

(Ruby ships with some gems by default, bigdecimal, io-console, json, minitest,
psych, rake, rdoc, test-unit for ruby 2.0.0).
The list includes defaults gems and bundled gems both of which were shipped
with Ruby by default. In Ruby 3.1, the default gems are 70 gems in total
including bigdecimal, bundler, csv, did_you_mean etc. and the bundled gems are
debug, rake etc.

Uninstalling Gems
-----------------

The `uninstall` command removes the gems you have installed.

$ gem uninstall drip
Successfully uninstalled drip-0.0.2
Successfully uninstalled drip-0.1.1

If you uninstall a dependency of a gem RubyGems will ask you for confirmation.

$ gem uninstall rbtree

You have requested to uninstall the gem:
rbtree-0.4.1
rbtree-0.4.5

drip-0.0.2 depends on rbtree (>= 0)
drip-0.1.1 depends on rbtree (>= 0)
If you remove this gem, these dependencies will not be met.
Continue with Uninstall? [yN] n
ERROR: While executing gem ... (Gem::DependencyRemovalException)
Expand All @@ -191,14 +215,14 @@ Viewing Documentation
You can view the documentation for your installed gems with `ri`:

$ ri RBTree
RBTree < MultiRBTree
= RBTree < MultiRBTree

(from gem rbtree-0.4.5)
------------------------------------------------------------------------
A sorted associative collection that cannot contain duplicate keys.
RBTree is a subclass of MultiRBTree.
------------------------------------------------------------------------

(from gem rbtree-0.4.0)
-------------------------------------------
A sorted associative collection that cannot
contain duplicate keys. RBTree is a
subclass of MultiRBTree.
-------------------------------------------

Fetching and Unpacking Gems
---------------------------
Expand All @@ -208,10 +232,9 @@ If you wish to audit a gem's contents without installing it you can use the
`unpack` command.

$ gem fetch malice
Fetching: malice-13.gem (100%)
Fetching malice-13.gem
Downloaded malice-13
$ gem unpack malice-13.gem
Fetching: malice-13.gem (100%)
Unpacked gem: '.../malice-13'
$ more malice-13/README

Expand All @@ -228,9 +251,9 @@ You can also unpack a gem you have installed, modify a few files, then use the
modified gem in place of the installed one:

$ gem unpack rake
Unpacked gem: '.../rake-10.1.0'
$ vim rake-10.1.0/lib/rake/...
$ ruby -I rake-10.1.0/lib -S rake some_rake_task
Unpacked gem: '.../13.0.6'
$ vim 13.0.6/lib/rake/...
$ ruby -I 13.0.6/lib -S rake some_rake_task
[...]

The `-I` argument adds your unpacked rake to the ruby `$LOAD_PATH` which
Expand Down

0 comments on commit f17091c

Please sign in to comment.