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<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Intro to Ruby ~ Girl Develop It</title>
<meta name="description" content="This is the official Girl Develop It Core Intro to Ruby course. The course is meant to be taught in five two-hour sessions. Each of the slides and practice files are customizable according to the needs of a given class or audience.">
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</head>
<body>
<div class="reveal">
<!-- Any section element inside of this container is displayed as a slide -->
<div class="slides">
<!-- Opening slide -->
<section>
<img src = "images/gdi_logo_badge.png">
<h3>Intro to Ruby</h3>
<h4>Class 4</h4>
</section>
<section>
<h3>Welcome!</h3>
<div class = "left-align">
<p>Girl Develop It is here to provide affordable and accessible programs to learn software through mentorship and hands-on instruction.</p>
<p class ="green">Some "rules"</p>
<ul>
<li>We are here for you!</li>
<li>Every question is important</li>
<li>Help each other</li>
<li>Have fun</li>
</ul>
</div>
</section>
<!-- Homework Review - 10 min -->
<section>
<h3>Homework Discussion</h3>
<p>How was last week's homework? Do you have any questions or concepts that you'd like to discuss?</p>
</section>
<section>
<h3>HW: English Numbers</h3>
<p>You could expand the EnglishNumbers program by adding the following code to deal with thousands:</p>
<pre><code class="ruby">
left = number # this line was original code, setting the 'left' variable
write = left/1000 # How many thousands left to write out?
left = left - write*1000 # Subtract off those thousands.
if write > 0
thousands = englishNumber write
numString = numString + thousands + ' thousand'
if left > 0
numString = numString + ' '
end
end
write = left/100 # this line begins the existing code that deals with hundreds
</code></pre>
</section>
<section>
<h3>HW: Wedding Numbers</h3>
<p>You could modify the code in the EnglishNumbers program to make it WeddingNumbers by replacing some of the added spaces with added 'and's and spaces: </p>
<pre><code class="ruby">
# numString = numString + ' ' # old code
numString = numString + ' and '
</code></pre>
</section>
<section>
<h3>HW: 99 Bottles of Beer</h3>
<p>You could modify the code for 99 Bottles of Beer shown in Class2 to include the functionality in the EnglishNumber class: </p>
<pre><code class="ruby">
require_relative 'englishnumber.rb'
num_bottles = 999
while num_bottles > 0
puts "#{englishNumber(num_bottles)} bottles of beer on the wall,
#{englishNumber(num_bottles)} bottles of beer, take one down, pass it
around, #{englishNumber(num_bottles - 1)} bottles of beer on the wall!"
num_bottles = num_bottles - 1
end
</code></pre>
</section>
<section>
<h3>Review</h3>
<ul>
<li>What is a method?</li>
<li>Creating & calling a method</li>
<li>What is an object?</li>
</ul>
<p>What would you like to see reviewed?</p>
</section>
<!-- Built in classes of Ruby: 20 minutes -->
<section>
<h3>Built in classes of Ruby</h3>
<p>Ruby has many classes predefined:</p>
<ul>
<li>String</li>
<li>Integer</li>
<li>Float</li>
<li>Array</li>
<li>Hash</li>
</ul>
<p>They are commonly used object types, and have methods associated with them already. How convenient!</p>
<pre><code contenteditable class="fragment ruby">
a = Array.new
b = String.new
</code></pre>
</section>
<section>
<h3>Built in classes of Ruby</h3>
<p>When we create new objects from these classes, we can do things with them immediately.</p>
<p>To see all methods associated with an object or class, run ".methods" on it.</p>
<pre><code contenteditable class="fragment ruby">
b = "holy cow!"
b.methods
</code></pre>
<p>You can view all the built in classes and their associated methods in the <a href="http://www.ruby-doc.org/core-2.0.0/" alt="Ruby docuemntation">Ruby documentation</a>.</p>
</section>
<section>
<h3>Extending a Class</h3>
<p>You can write new methods for the built in classes of Ruby. They will then be available to all instances of that class in your program.</p>
<pre><code contenteditable class="fragment ruby">
class String
def get_excited
wow = self + "!!!"
return wow
end
end
</code></pre>
<p>"self" refers to the object calling the method.</p>
<p>You can redefine existing methods for classes this way, too, but it's not recommended.</p>
</section>
<!-- Creating a class: 20 minutes -->
<section>
<h3>Creating a Class</h3>
<p>It's very easy to create your own classes in Ruby.</p>
<pre><code contenteditable class="fragment ruby">
# die.rb
class Die
def roll
@numberShowing = 1 + rand(6)
#rand(6) returns a random-ish number between 0-5
end
def showing
return @numberShowing
end
end
</code></pre>
<p>Inside the class, define its methods.</p>
</section>
<section>
<h3>Creating a Class</h3>
<p>You can use your class right away by loading it into IRB.</p>
<pre><code>
#in irb
load 'die.rb'
die = Die.new
die.roll
puts die.showing
</code></pre>
<p>You can use it in another file by requiring it. We'll discuss this later.</p>
<!-- pause here til everyone's got this working -->
</section>
<section>
<h3>Refactoring a Class</h3>
<p>What is the result of calling the .showing method on a newly-created, un-rolled Die object?</p>
<p>We can avoid this by calling the roll method as part of the creation of a new instance of Die.</p>
<pre><code class="fragment ruby">
# die.rb
class Die
def initialize
roll
end
def roll
@numberShowing = 1 + rand(6)
end
def showing
@numberShowing
end
end
</code></pre>
</section>
<!-- Let's develop it: 10 minutes -->
<section>
<h3>Let's Develop It</h3>
<ul>
<li>In your text editor, create your own class with an initialize method, and at least one other method.</li>
<li>Open IRB and load the class. Create one or more objects from the class and run some methods on them.</li>
<li>You could use the next slides as an example.</li>
</ul>
</section>
<section>
<h3>Example of creating a class</h3>
<pre><code contenteditable class="ruby">
# in character.rb
class Character
def initialize(name)
@name = name
@health = 10
end
def heal
@health += 6
end
def adventure
if @health > 0
puts "#{@name} goes on a great adventure and meets a dragon!"
puts "The dragon hugged #{@name} kind of hard..."
@health -= 5
else
puts "#{@name} is dead :("
exit
end
end
end
</code></pre>
</section>
<section>
<h3>Running example program in IRB</h3>
<pre><code contenteditable class="ruby">
# in irb
load 'character.rb'
me = Character.new("Cheri")
me.adventure
me.heal
me.adventure
# repeat until you're done having fun
</code></pre>
</section>
<!-- Putting it together: 10 minutes -->
<section>
<h3>Inheritance</h3>
<p>Classes can <strong>inherit</strong> from one other class.</p>
<p>All elves are characters, so if all characters have an adventure method, so do all elves. Elves may also have their own methods that other characters do not.</p>
</section>
<section>
<h3>Inheritance</h3>
<p>Denote that Elf inherits from Character by using the < symbol</p>
<pre><code class="fragment ruby">
# in character.rb, after Character class code
class Elf < Character
def twinkle
puts "I'm super magical!"
end
end
#in irb
load 'character.rb'
me = Elf.new("Cheri")
me.adventure
me.twinkle
</code></pre>
<p>Notice that the initialize method was also inherited, as our new Elf knows its name and started off with 10 health.</p>
</section>
<section>
<h3>Inheritance</h3>
<p><strong>Subclasses</strong> may differ from from their <strong>super classes</strong> in some ways. Methods can be overwritten when this is the case.</p>
<pre><code contenteditable class="fragment ruby">
# in character.rb, after Character class code
class Elf < Character
def twinkle
puts "I'm super magical!"
end
def heal
@health += 8 # it's easier to heal when you're magic
end
end
#in irb
load 'character.rb'
me = Elf.new("Cheri")
me.heal
</code></pre>
<p>More information about inheritance can be found <a href="http://rubylearning.com/satishtalim/ruby_inheritance.html" alt="rubylearning.com">here</a>.</p>
</section>
<section>
<h3>Putting it all together</h3>
<p>For a command line program, you need these pieces:</p>
<ol>
<li>File(s) containing your class definitions</li>
<li>A file containing your program, which requires the class file(s)</li>
<li>To call the program file from the command line (not IRB)</li>
</ol>
</section>
<section>
<h3>Putting it all together</h3>
<p>The file containing your class definitions, here called character.rb: </p>
<pre><code contenteditable class="ruby">
# in character.rb
class Character
# contents of class here
end
class Elf < Character
# contents of class here
end
</code></pre>
</section>
<section>
<h3>Putting it all together</h3>
<p>The file containing your program, here called adventure.rb, which requires the class file: </p>
<pre><code contenteditable class="ruby">
# in adventure.rb
require_relative 'character.rb'
#file path relative to the location of adventure.rb file
require_relative 'die.rb'
puts "Your name?"
char = Character.new(gets.chomp)
# plus lots more adventuring.....
</code></pre>
</section>
<section>
<h3>Putting it all together</h3>
<p>Call the program file from the command line: </p>
<pre><code contenteditable class="ruby">
#in command line
ruby adventure.rb
# then have some fun!
</code></pre>
</section>
<!-- Let's develop it: 40 minutes -->
<section>
<h3>Let's Develop It</h3>
<p>Putting it all together: A role-playing game!</p>
<ul>
<li>If you didn't write a Character class, copy and paste the code to get one started.</li>
<li>Create a few subclasses of Character.</li>
<li>Write a command-line program that calls your character and die classes to allow the user to have an adventure!</li>
<li>Maybe user can choose their character type?</li>
<li>Maybe the user's progress will be dependent on outcome of dice-rolling?</li>
</ul>
</section>
<section>
<h3>Questions?</h3>
</section>
<!-- Wrap up: 10 minutes -->
<section>
<h3>Further Resources</h3>
<table style="font-size: 24px; line-height: 1.5em;">
<tr>
<td><a href="http://www.ruby-doc.org/">Ruby-doc.org</a></td>
<td>Official Ruby Documentation</td>
</tr>
<tr>
<td><a href="https://projecteuler.net">Project Euler</a></td>
<td>Offers tons of small math problems to be solved via programming, plus forums to share and discuss solutions</td>
</tr>
<tr>
<td><a href="https://rubymonk.com/">Ruby Monk</a></td>
<td>Free, interactive, in-browser tutorials</td>
</tr>
<tr>
<td><a href="http://ruby.learncodethehardway.org/">Ruby the Hard Way</a></td>
<td>Fun, free (HTML version) book with great information about programming</td>
</tr>
<tr>
<td><a href="http://www.sinatrarb.com/">Sinatra</a></td>
<td>A basic web app framework that runs on Ruby</td>
</tr>
<tr>
<td><a href="http://ruby.railstutorial.org/">The Rails Tutorial</a></td>
<td>The Rails web app framework is the most popular use of Ruby... are you ready to dive in?</td>
</tr>
<tr>
<td><a href="http://girldevelopit.com/">Girl Develop It</a></td>
<td>Local workshops, events, and coding sessions with awesome people</td>
</tr>
</table>
</section>
<section>
<h3>Homework</h3>
<p><strong>Practice:</strong> Make your final project even bigger and better! If you're taking this class as part of a job plan, attend a local meetup and talk to a couple of strangers about what you've learned and what you're excited about doing with programming. </p>
</section>
</div>
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Intro to Ruby
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