ruby presentation - beamer

The Language Tools

Ruby: Why We Love Ithttps://github.com/Kelsin/ruby-presentation

Christopher Giroir

November 8th, 2011

Christopher Giroir Ruby: Why We Love It

The Language Tools

1 The LanguageBasicsWhy We Love ItGems

2 ToolsBundlerRVM

The Language Tools

Basics

Overview

Inspired by Smalltalk (which I love)

Also draws from Perl, Eiffel, Ada and LISP

Includes a REPL

Built for developers as a language they would love to use

Dynamic, strict, reflective, object oriented

Everything is an expression (even statements)

Everything is executed imperatively (even declarations)

The Language Tools

Basics

Overview

Includes a REPL

The Language Tools

Basics

Overview

Includes a REPL

The Language Tools

Basics

Overview

Includes a REPL

The Language Tools

Basics

Overview

Includes a REPL

The Language Tools

Basics

Overview

Includes a REPL

The Language Tools

Basics

Overview

Includes a REPL

The Language Tools

Basics

Object Oriented

Everything is an object

Single Inheritance

Modules can be mixed in

Dynamic Dispatch

The Language Tools

Basics

Object Oriented

Single Inheritance

Dynamic Dispatch

The Language Tools

Basics

Object Oriented

Single Inheritance

Dynamic Dispatch

The Language Tools

Basics

Object Oriented

Single Inheritance

Dynamic Dispatch

The Language Tools

Basics

Simple Code

1 5.times { print "Hello" }

This outputs:

1 Hello

2 Hello

3 Hello

4 Hello

5 Hello

6 => 5

The Language Tools

Basics

Simple Code

1 5.times { print "Hello" }

This outputs:

1 Hello

2 Hello

3 Hello

4 Hello

5 Hello

6 => 5

The Language Tools

Basics

1 # Strings

2 s = ’Testing’

4 # Interpreted Strings

5 t = "Double #{str}"

7 # Symbols

8 sym = :chris

10 # Arrays

11 a = [1,2,3]

13 # Hashes

14 h = { :key => ’value’, :chris => ’awesome’ }

The Language Tools

Basics

Classes

1 class Box

2 def initialize(w,h,d)

3 @width = w

4 @height = h

5 @depth = d

8 def volume

9 @width * @height * @depth

10 end

11 end

13 box = Box.new(2,2,2)

14 box.volume # => 8

The Language Tools

Basics

Simple Inheritance

1 class JackInTheBox < Box

2 def initialize(msg)

3 @msg = msg

4 super(3,3,3)

7 def open

8 puts @msg

10 end

12 jbox = JackInTheBox.new(’Surprise!’)

13 jbox.volume # => 27

14 jbox.open # prints ’Surprise!’

The Language Tools

Basics

Control

1 while true == false

2 if var == 5

3 break

6 begin

7 var - 1

8 end while var < 4

10 next if var == 6

11 end

The Language Tools

Basics

Blocks

1 [1,2,3].each { |n| puts n }

This outputs:

4 => [1,2,3]

The Language Tools

Basics

Blocks

1 [1,2,3].each { |n| puts n }

This outputs:

4 => [1,2,3]

The Language Tools

Basics

Block Syntax

1 5.upto(10) { |n| puts n }

This is exactly the same as the following:

1 5.upto(10) do |n|

2 puts n

The Language Tools

Why We Love It

Attribute Methods

1 class Person

2 def name

3 @name

5 def social=(s)

6 @social = s

8 def age

9 @age

10 end

11 def age=(a)

12 @age = a

13 end

14 end

The Language Tools

Why We Love It

The Easy Way

1 class Person

2 attr_reader :name

3 attr_writer :social

4 attr_accessor :age

The Language Tools

Why We Love It

The Easy Way Explained

1 class Person

2 attr_reader :name

Ruby syntax allows method calls without ()

Result is clean and looks like a language feature

The Language Tools

Why We Love It

The Easy Way Explained

1 class Person

2 attr_reader :name

Ruby syntax allows method calls without ()

Result is clean and looks like a language feature

The Language Tools

Why We Love It

We can implement this ourselves

Untested code, please do not copy:

1 class Object

2 def self.attr_reader(var)

3 class_eval <<-METHODS

4 def #{var}

5 @#{var}

7 METHODS

The Language Tools

Why We Love It

We can implement this ourselves

Untested code, please do not copy:

1 class Object

2 def self.attr_reader(var)

3 class_eval <<-METHODS

4 def #{var}

5 @#{var}

7 METHODS

The Language Tools

Why We Love It

Why Blocks

1 (map (lambda (n)

2 (+ n 5))

3 ’(1 2 3))

Becomes:

1 [1,2,3].map do |n|

2 n + 5

Results in:

1 => [6,7,8]

The Language Tools

Modules

1 module Voice

2 def say(msg)

3 puts msg

7 class Person

8 include Voice

11 p = Person.new

12 p.say(’Hello’) # prints ’Hello’

The Language Tools

Using Gems

Require loads in files

1 require ’saver’ # pulls in ’saver.rb’

Gems allow us to not deal with paths

1 require ’rubygems’

2 require ’saver’

4 class Item

5 include Saver

The Language Tools

Writing Gems

1 Gem::Specification.new do |s|

2 s.name = "saver"

3 s.version = Saver::VERSION

4 s.authors = ["Christopher Giroir"]

5 s.email = ["[email protected]"]

6 s.homepage = "http://kelsin.github.com/saver/"

8 s.files = ‘git ls-files‘.split("\n")

9 s.require_paths = ["lib"]

11 s.add_dependency ’activesupport’, ’~> 3.0.0’

12 s.add_dependency ’mongo_mapper’

13 end

The Language Tools

Bundler

Why Bundler?

Many projects (i.e. rails apps) are not gems themselves

They do have gem dependencies

Easy way to install and keep track of these dependencies

Making sure ONLY the proper gems are used

The Language Tools

Bundler

Why Bundler?

The Language Tools

Bundler

Why Bundler?

The Language Tools

Bundler

The Gemfile

1 source ’http://tools1.savewave.com/rubygems’

2 source ’http://rubygems.org’

4 gem ’rails’, ’3.0.7’

6 gem ’sw-model’, ’0.13.0’

8 group :development, :test do

9 gem "rspec"

10 end

The Language Tools

Bundler

Using Bundler

1 # Install the gems from the Gemfile

2 bundle install

4 # Update gems to new versions

5 bundle update

7 # Execute command with proper gems

8 bundle exec rake spec

In your ruby code

1 require "rubygems"

2 require "bundler/setup"

3 require "saver"

The Language Tools

Bundler

Gemfile.lock

When you initially install versions are saved to Gemfile.lock

After they are only updated on bundle update

SHOULD be checked into version control

Protects from version updates

The Language Tools

Bundler

Gemfile.lock

The Language Tools

Bundler

Gemfile.lock

The Language Tools

Why RVM?

Different projects might use different versions of rails

Different projects might use different ruby interpreters

RubyJRubyRubinus

While bundler helps, complete gem isolation is better!

It’s nice to keep your system ruby separate and not update it

The Language Tools

Why RVM?

RubyJRubyRubinus

The Language Tools

Why RVM?

RubyJRubyRubinus

The Language Tools

Why RVM?

RubyJRubyRubinus

The Language Tools

Using RVM

1 # Install the default 1.9.2 ruby interpretor

2 rvm install 1.9.2

4 # Switch to using 1.9.2

5 rvm use 1.9.2

7 # List installed rubies

8 rvm list

The Language Tools

RVM Gemsets

1 # Create a new gemset

2 rvm gemset create savingstar-web

4 # List gemsets

5 rvm gemset list

7 # Switch to a ruby and gemset together

8 rvm use 1.9.2@savingstar-web

The Language Tools

.rvmrc

A .rvmrc file per project allows you to say which ruby andgemset to use

Should be in source control. Helps RVM users out, ignored forothers

It’s a shell script that’s executed everytime you cd (veryunsafe)

Makes life very easy however!

1 rvm use 1.9.2@saveingstar-web --create

The Language Tools

.rvmrc

The Language Tools

.rvmrc

The Language Tools

.rvmrc

The Language Tools

.rvmrc

ruby presentation - beamer

Technology

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