Rubygems And You

RubyGems and You

Josh Nichols technicalpickles.com

Overview

• How ‘require’ works
• Where rubygems ﬁts in
• Creating your own rubygem from scratch
• Creating your own rubygem using jeweler


require
executes the contents of a ﬁle


# foo.rb
puts quot;zomg, so awesomequot;

# bar.rb
require 'foo.rb'

$ ruby bar.rb
zomg, so awesome


require ‘/usr/lib/awesome.rb’
absolute path


require ‘subdir/foo.rb’
relative path


require ‘subdir/foo’
can omit the .rb


$LOAD_PATH
list of directories to look for required ﬁles


require ‘net/http’
$LOAD_PATH includes your ruby install....
this actually lives under a path like:
/usr/local/lib/ruby/1.8/


require
only will execute a particular path once


# foo.rb
puts quot;zomg, so awesomequot;

# bar.rb
require 'foo'
require 'foo'
require './foo'

$ ruby bar.rb
zomg, so awesome
zomg, so awesome


Dealing with diversity...

• Different environments (mac vs. win. vs. linux)
• People install stuff to random places
• Different versions of libraries
• What do we do?


MASS HYSTERIA!

Enter RubyGems

• Handles downloading and installing library
• Manages $LOAD_PATH
• Allows a developer to package & distribute their library


Installing

• gem install burninator


Using gems

require 'rubygems'
require 'burninator'


Using gems in under Rails

# config/environment.rb, or anywhere really
require 'burninator'



# config/environment.rb
config.gem 'burninator'



# create vendor/gems...
# then 'gem unpack' gems there
# config/environment.rb
Rails::Initializer.run do |config|
config.load_paths += Dir[quot;#{RAILS_ROOT}/vendor/gems/**quot;].map do |dir|
File.directory?(lib = quot;#{dir}/libquot;) ? lib : dir
end
end


Where do gems live?


• RubyGems already knows about it by default
• Has been the defacto standard for hosting


• But you need to apply for projects...
• And you need extra tools to publish gems...


• The new hotness
• Just create a repository and turn on RubyGem support
• Create a Gem::Speciﬁcation, and push it


Tools of the trade

• Rake for automation
• Testing framework of choice (we’ll assume test/unit)
• RubyGems


Rakeﬁle basics

require 'rubygems'
require 'rake'


Gem::Speciﬁcation

• Metadata about your gem
• name, ﬁles, binaries, homepage, etc, etc


Rakeﬁle gemspec
spec = Gem::Specification.new do |s|
s.name = 'cylon-detector'
s.version = '0.8.1'
s.authors = ['Josh Nichols']
s.date = '2009-02-03'
s.email = 'josh@technicalpickles.com'
s.files = FileList['{bin,lib}/**']
s.executables = 'cylon_detector'
s.has_rdoc = true
s.summary = 'Detect cylons with ease'
end


Rakeﬁle gemspec

task :gemspec do
File.open('cylon-detector.gemspec', 'w') do |file|
file.write spec.to_ruby
end
end


Rakeﬁle package

require 'rake/gempackagetask'
Rake::GemPackageTask.new(spec) do |pkg|
pkg.need_zip = false
pkg.need_tar = false
end


Rakeﬁle rdoc

require 'rake/rdoctask'
Rake::RDocTask.new do |rdoc|
rdoc.rdoc_dir = 'rdoc'
rdoc.title = 'cylon-detector'
rdoc.options << '--line-numbers' << '--inline-source'
rdoc.rdoc_files.include('README.rdoc')
rdoc.rdoc_files.include('lib/**/*.rb')
end


Rakeﬁle test

require 'rake/testtask'
Rake::TestTask.new(:test) do |t|
t.test_files = 'test/**/test_*.rb'
t.verbose = false
end


Rakeﬁle rcov

begin
require 'rcov/rcovtask'
Rcov::RcovTask.new do |t|
t.test_files = 'test/**/test_*.rb'
t.verbose = true
end
rescue LoadError
task :rcov do
abort quot;RCov is not available. In order to run rcov, you must: sudo gem install spicycode-rcovquot;
end
end


Rakeﬁle default

task :default => :test


bin/cylon_detector

#!/usr/bin/env ruby

$LOAD_PATH.unshift(File.join(File.dirname(__FILE__), '..', 'lib'))
require 'cylon_detector'

# detection code here


lib/cylon_detector.rb

• The entry point into your library
• Require all dependencies (internal and external)
• Design decisions
• generally want to namespace your project
• class or module?
• Do not require rubygems (unless you are interacting
directly with it)


test/test_helper.rb

• Central location to setup testing environment
require 'rubygems'
require 'test/unit'

$LOAD_PATH.unshift(File.join(File.dirname(__FILE__), '..', 'lib'))
$LOAD_PATH.unshift(File.dirname(__FILE__))

require 'cylon_detector'

class Test::Unit::TestCase
end


test/test_cylon_detector.rb

require File.dirname(__FILE__) + '/test_helper'

class CylonDetectorTest < Test::Unit::TestCase
# tests go here
end


Workﬂow

• Hack and commit your code
• ‘rake gemspec’ and commit your gemspec
• push to GitHub
• wait for the gem to build
• rejoice and have some Scotch


Jeweler

• Handles the grunt work
• Generator
• Skeleton project setup for your test framework of choice
• Starts a git repo setup for GitHub
• Creates the repo on GitHub and enables RubyGem for it
• Rake tasks
• Automate version bumping
• Releasing to GitHub, including tagging the release


Generator

• Choose between testing frameworks
• Test::Unit
• Shoulda
• RSpec
• Bacon
• Also includes cucumber stories enabled for


Versioning

• Tracks current version in VERSION.yml
• Rake tasks for bumping the version
• version:bump:patch, version:bump:minor,
version:bump:major


0.8.5
patch version
API backward-compatible
bug ﬁxes
minor enhancements


0.8.5
minor version
mostly API backwards compatible
more signiﬁcant enhancements


0.8.5
major version
break API as much you want
usually signiﬁes an overhaul


Releasing

• Updates the gemspec based on the version
• Pushes to GitHub
• Tags the release with the version number


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