Stop Reinventing The Wheel - The Ruby Standard Library

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

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

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/

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

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

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

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

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

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

Ruby Standard Library http://ruby-doc.org/stdlib/ Twitter: @bphogan Web: http://www.napcs.com/

•FileUtils •Forwardable •Pathname •open-uri •TempFile •WEBrick Twitter: @bphogan Web: http://www.napcs.com/

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/

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/

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

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

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

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

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/

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/

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/

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

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

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

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/

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/

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/

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/

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

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

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

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

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/

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

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

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

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/

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/

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

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

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/

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/

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

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

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

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

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/

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/

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/

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/

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

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

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

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/

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

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

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

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

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

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

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/

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/

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

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

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

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

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

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

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/

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/

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

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

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

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

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

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

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

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

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

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

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

“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/

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

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

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

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

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

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

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/

Stop Reinventing The Wheel - The Ruby Standard Library

by Brian Hogan on Sep 05, 2010

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Stop Reinventing The Wheel - The Ruby Standard Library — Presentation Transcript

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