1. stop reinventing
the wheel
hidden gems in the ruby standard library
brian hogan - @bphogan

2. Twitter: @bphogan
Web: http://www.napcs.com/

3. What about this
design?
describe "the user" do
it "gets an email when their account is activated" do
# some stuff
end
end
Twitter: @bphogan
Web: http://www.napcs.com/

4. Sometimes ideas
evolve for the better.
Twitter: @bphogan
Web: http://www.napcs.com/

5. Other times not so
much.
Twitter: @bphogan
Web: http://www.napcs.com/

6. In software we
reinvent
Twitter: @bphogan
Web: http://www.napcs.com/

7. How often is
“better”
really just opinion?
Twitter: @bphogan
Web: http://www.napcs.com/

8. So, we’re not talking
about always using
what exists...
Twitter: @bphogan
Web: http://www.napcs.com/

9. We’re talking about
reinventing because
of ignorance, hubris,
or ego.
Twitter: @bphogan
Web: http://www.napcs.com/

10. Ruby Standard Library
http://ruby-doc.org/stdlib/
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11. •FileUtils
•Forwardable
•Pathname
•open-uri
•TempFile
•WEBrick
Twitter: @bphogan
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12. Working With The File
System
system("mkdir -p tmp/files")
system("touch tmp/files/lockfile.lock")
system("rm -rf tmp/files")
Twitter: @bphogan
Web: http://www.napcs.com/

13. Make it platform-
independent!
require 'fileutils'
FileUtils.mkdir_p("tmp/files")
FileUtils.touch("tmp/files/lockfile.lock")
FileUtils.rm_rf("tmp/files")
Twitter: @bphogan
Web: http://www.napcs.com/

14. FileUtils
Namespace for several file utility methods
for copying, moving, removing, etc.
Twitter: @bphogan
Web: http://www.napcs.com/

15. Where it’s used
•Rake
•Capistrano stuff
•Sinatra Reloader gem
•Compass
Twitter: @bphogan
Web: http://www.napcs.com/

16. Where does it fall
short?
Twitter: @bphogan
Web: http://www.napcs.com/

17. Delegating Methods
Calling methods on one class through another.
User Profile
name name
Twitter: @bphogan
Web: http://www.napcs.com/

18. Here’s how Rails
does it
def delegate(*methods)
options = methods.pop
unless options.is_a?(Hash) && to = options[:to]
raise ArgumentError, "Delegation needs a target.
Supply an options hash with a :to key as the last argument
(e.g. delegate :hello, :to => :greeter)."
end
methods.each do |method|
module_eval("def #{method}(*args, &block)
n#{to}.__send__(#{method.inspect},
*args, &block)nendn", "(__DELEGATION__)", 1)
end
end
Twitter: @bphogan
Web: http://www.napcs.com/

19. Here’s how Rails
does it
class User < ActiveRecord::Base
has_one :profile
delegate :name, :to => :profile
end
Twitter: @bphogan
Web: http://www.napcs.com/

20. Here’s how we could
do it.
require 'forwardable'
class User < ActiveRecord::Base
has_one :profile
extend Forwardable
def_delegator :profile, :bio, :bio
end
Twitter: @bphogan
Web: http://www.napcs.com/

21. Forwardable
This library allows you
delegate method calls to
an object, on a method by
method basis.
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Web: http://www.napcs.com/

22. Where it’s used
•MongoMapper
•Rack::Client
Twitter: @bphogan
Web: http://www.napcs.com/

23. Where does it fall
short?
Twitter: @bphogan
Web: http://www.napcs.com/

24. Working with Paths
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Web: http://www.napcs.com/

25. Seen in tons of Rails
apps...
file = File.join(RAILS_ROOT, "config", "database.yml")
config = YAML.load(File.read(file))
Twitter: @bphogan
Web: http://www.napcs.com/

26. A better way
file = Rails.root.join("config", "database.yml")
config = YAML.load(file.read)
Rails.root.class
=> Pathname
http://litanyagainstfear.com/blog/2010/02/03/the-rails-module/
Twitter: @bphogan
Web: http://www.napcs.com/

27. Pathname
Library to simplify working
with files and paths.
Represents a pathname which locates a file
in a filesystem. The pathname depends on
OS: Unix, Windows, etc.
Twitter: @bphogan
Web: http://www.napcs.com/

28. Neat stuff
require 'pathname'
p = Pathname.new("/usr/bin/ruby")
size = p.size # 27662
isdir = p.directory? # false
dir = p.dirname # Pathname:/usr/bin
base = p.basename # Pathname:ruby
dir, base = p.split # [Pathname:/usr/bin, Pathname:ruby]
Twitter: @bphogan
Web: http://www.napcs.com/

29. Where it’s used
•Rails
•DataMapper
•Warehouse
•Webistrano
•many many more
Twitter: @bphogan
Web: http://www.napcs.com/

30. Grabbing Files
Twitter: @bphogan
Web: http://www.napcs.com/

31. cURL?
puts `curl http://pastie.org/1131498.txt?
key=zst64zkddsxafra0jz678g`
Twitter: @bphogan
Web: http://www.napcs.com/

32. Not available
everywhere,
must handle redirects.
Twitter: @bphogan
Web: http://www.napcs.com/

33. Treat URLs as files!
require 'open-uri'
url = "http://pastie.org/1131498.txt?key=zst64zkddsxafra0jz678g"
puts open(url).read
Twitter: @bphogan
Web: http://www.napcs.com/

34. open-uri
Wraps net/http, net/https, and net/ftp.
Twitter: @bphogan
Web: http://www.napcs.com/

35. Where it’s used
•Everywhere.
Twitter: @bphogan
Web: http://www.napcs.com/

36. Where does it fall
short?
Twitter: @bphogan
Web: http://www.napcs.com/

37. Temporary files
Twitter: @bphogan
Web: http://www.napcs.com/

38. The hard way
path = "http://pastie.org/1131498.txt?key=zst64zkddsxafra0jz678g"
`curl #{path} > /tmp/template.html`
s = File.read("/tmp/template.html")
puts s
Twitter: @bphogan
Web: http://www.napcs.com/

39. Use TempFile
require 'open-uri'
require 'tempfile'
url = "http://pastie.org/1131498.txt?key=zst64zkddsxafra0jz678g"
tempfile = Tempfile.new("template.html")
tempfile.write open(url).read
puts tempfile.open.read
Twitter: @bphogan
Web: http://www.napcs.com/

40. Where it’s used
•File uploading
•Caching
Twitter: @bphogan
Web: http://www.napcs.com/

41. Data structures
Twitter: @bphogan
Web: http://www.napcs.com/

42. YAML loads to hashes
require 'YAML'
config = YAML.load(Pathname.new("config.yml").read)
puts config["company_name"]
puts config["banner_image_url"]
puts config["custom_css_url"]
Twitter: @bphogan
Web: http://www.napcs.com/

43. Use OpenStruct!
require 'ostruct'
require 'YAML'
config = YAML.load(Pathname.new("config.yml").read)
config = OpenStruct.new(config)
puts config.company_name
puts config.banner_image_url
puts config.custom_css_url
Twitter: @bphogan
Web: http://www.napcs.com/

44. Don’t write your own
“YAML-to-Object”
thing (like I once did!)
Twitter: @bphogan
Web: http://www.napcs.com/

45. Where it’s used
•Fat Free CMS
•ActiveMessaging
•Adhearsion
•AASM
Twitter: @bphogan
Web: http://www.napcs.com/

46. Where does it fall
short?
Twitter: @bphogan
Web: http://www.napcs.com/

47. Watching Stuff
Twitter: @bphogan
Web: http://www.napcs.com/

48. Rails?
Twitter: @bphogan
Web: http://www.napcs.com/

49. def initialize
super
observed_descendants.each { |klass| add_observer!(klass) }
end
def self.method_added(method)
method = method.to_sym
if ActiveRecord::Callbacks::CALLBACKS.include?(method)
self.observed_methods += [method]
self.observed_methods.freeze
end
end
protected
def observed_descendants
observed_classes.sum([]) { |klass| klass.descendants }
end
def observe_callbacks?
self.class.observed_methods.any?
end
def add_observer!(klass)
super
define_callbacks klass if observe_callbacks?
end
def define_callbacks(klass)
existing_methods = klass.instance_methods.map { |m| m.to_sym }
observer = self
observer_name = observer.class.name.underscore.gsub('/', '__')
self.class.observed_methods.each do |method|
callback = :"_notify_#{observer_name}_for_#{method}"
unless existing_methods.include? callback
klass.send(:define_method, callback) do # def _notify_user_observer_for_before_save
observer.update(method, self) # observer.update(:before_save, self)
end # end
klass.send(method, callback) # before_save :_notify_user_observer_for_before_save
end
end
end
end
end
Twitter: @bphogan
Web: http://www.napcs.com/

50. Observer
Provides a simple
mechanism for one
object to inform a set of
interested third-party
objects when its state
changes.
Twitter: @bphogan
Web: http://www.napcs.com/

51. How we do it
require 'observer'
class ConfirmationEmailer
def update(account)
puts "Sending confirmation mail to: '#{account.email}'"
# send the email mechanism
end
end
Twitter: @bphogan
Web: http://www.napcs.com/

52. class Account
include Observable
attr_accessor :email, :active
def initialize(email)
self.email = email
self.active = false
add_observer ConfirmationEmailer.new
end
def activate_account!
self.active = true
changed # <- This is important
notify_observers self
end
end
Twitter: @bphogan
Web: http://www.napcs.com/

53. Where does it fall
short?
Twitter: @bphogan
Web: http://www.napcs.com/

54. Serving Web Pages
Twitter: @bphogan
Web: http://www.napcs.com/

55. Sinatra?
require 'sinatra'
set :public, "~/Sites"
Twitter: @bphogan
Web: http://www.napcs.com/

56. How about this?
s = WEBrick::HTTPServer.new(:Port => 3000,
:DocumentRoot => "~/Sites")
trap('INT') { s.shutdown };
s.start
Twitter: @bphogan
Web: http://www.napcs.com/

57. How about an alias?
alias serve="ruby -rwebrick -e"s = WEBrick::HTTPServer.new(:Port => 3000, :DocumentRoot =>
Dir.pwd); trap('INT') { s.shutdown }; s.start""
$ cd ~/Sites
$ serve
Twitter: @bphogan
Web: http://www.napcs.com/

58. Twitter: @bphogan
Web: http://www.napcs.com/

59. It also serves web
apps
Twitter: @bphogan
Web: http://www.napcs.com/

60. Your dev machine
really needs Passenger
running?
Twitter: @bphogan
Web: http://www.napcs.com/

61. Where it’s used
•Rails
•Other frameworks
Twitter: @bphogan
Web: http://www.napcs.com/

62. Where does it fall
short?
Twitter: @bphogan
Web: http://www.napcs.com/

63. Storing Data
Twitter: @bphogan
Web: http://www.napcs.com/

64. PStore
Persistent, transactional
storage. Baked right in to
Ruby’s standard library.
Twitter: @bphogan
Web: http://www.napcs.com/

65. We can store stuff...
require 'pstore'
store = PStore.new('links')
links = %W{http://www.github.com
http://heroku.com
http://ruby-lang.org}
store.transaction do
store[:links] ||= []
links.each{|link| store[:links] << link}
store[:last_modified] = Time.now
end
Twitter: @bphogan
Web: http://www.napcs.com/

66. and we can get it
back.
store = PStore.new("links")
store.transaction do
links = store[:links]
end
puts links.join("n")
Twitter: @bphogan
Web: http://www.napcs.com/

67. Where it’s used
•Rails 1.x
Twitter: @bphogan
Web: http://www.napcs.com/

68. Where does it
fall short?
Twitter: @bphogan
Web: http://www.napcs.com/

69. Better Wheels
Twitter: @bphogan
Web: http://www.napcs.com/

70. Importing CSV files
require 'csv'
CSV.open('data.csv', 'r', ';') do |row|
p row
end
Twitter: @bphogan
Web: http://www.napcs.com/

71. CSV is slow.
“Use FasterCSV”
Twitter: @bphogan
Web: http://www.napcs.com/

72. In Ruby 1.9,
FasterCSV is the new
CSV!
Twitter: @bphogan
Web: http://www.napcs.com/

73. Working with Dates
Twitter: @bphogan
Web: http://www.napcs.com/

74. How we do it
today = DateTime.now
birthday = Date.new(2010, 10, 5)
days_to_go = birthday - today
time_until = birthday - today
hours,minutes,seconds,frac =
Date.day_fraction_to_time(time_until)
http://www.techotopia.com/index.php/Working_with_Dates_and_Times_in_Ruby
Twitter: @bphogan
Web: http://www.napcs.com/

75. home_run
home_run is an implementation of rubyʼs Date/
DateTime classes in C, with much better
performance (20-200x) than the version in the
standard library, while being almost completely
compatible.
http://github.com/jeremyevans/home_run
Twitter: @bphogan
Web: http://www.napcs.com/

76. REXML
Built-in library for
parsing and creating XML.
Twitter: @bphogan
Web: http://www.napcs.com/

77. How about
HPricot, libxml-
ruby, or
Nokogiri.
http://www.rubyinside.com/ruby-xml-performance-benchmarks-1641.html
Twitter: @bphogan
Web: http://www.napcs.com/

78. ERb
Templating language as part of the Standard Library.
Twitter: @bphogan
Web: http://www.napcs.com/

79. require 'erb'
template = ERB.new <<-EOF
<h1><%=@name %></h1>
EOF
@name = "AwesomeCo"
puts template.result
Twitter: @bphogan
Web: http://www.napcs.com/

80. Templating language
!=
View language!!!
Twitter: @bphogan
Web: http://www.napcs.com/

81. What can it do?
•Generate JavaScript
•Generate YAML
•Generate ERb
•Any type of proprietary data export
Twitter: @bphogan
Web: http://www.napcs.com/

82. Where does it fall
short?
Twitter: @bphogan
Web: http://www.napcs.com/

83. Alternatives?
•HAML
•Liquid
•ERubis
•Tons of others
Twitter: @bphogan
Web: http://www.napcs.com/

84. Test::Unit
We have an awesome testing library
as part of our standard library.
Twitter: @bphogan
Web: http://www.napcs.com/

85. It’s pretty good.
Anyone know of any
alternatives?
Twitter: @bphogan
Web: http://www.napcs.com/

86. Only a few.
•RSpec
•Bacon
•Context / Contest / Shoulda / Matchy
•Testy
•Micronaut
•Whatever someone writes next week
Twitter: @bphogan
Web: http://www.napcs.com/

87. I use RSpec *
* And I still use Test::Unit.
Twitter: @bphogan
Web: http://www.napcs.com/

88. “Minitest is a minitest/unit
is a small and fast
replacement for ruby's
huge and slow test/unit”.
Twitter: @bphogan
Web: http://www.napcs.com/

89. If X sucks so bad, why
do we write
something else
instead of fixing it?
Twitter: @bphogan
Web: http://www.napcs.com/

90. We think we can do it
better.
Twitter: @bphogan
Web: http://www.napcs.com/

91. The original developer
doesn’t want our help.
Twitter: @bphogan
Web: http://www.napcs.com/

92. There’s a language
barrier.
Twitter: @bphogan
Web: http://www.napcs.com/

93. Challenge:
Extend the Standard
Library.
Twitter: @bphogan
Web: http://www.napcs.com/

94. Make the wheels we
have better.
Twitter: @bphogan
Web: http://www.napcs.com/

95. That’s it.
•Twitter: @bphogan
•email: bphogan@gmail.com
•web: http://www.napcs.com/
•blog: http://bphogan.com
•github: http://github.com/napcs/
Twitter: @bphogan
Web: http://www.napcs.com/