# The Greeter class
class Greeter
  def initialize(name)
    @name = name.capitalize
  end

  def salute
    puts "Hello #{@name}!"
  end
end

# Create a new object
g = Greeter.new("world")

# Output "Hello World!"
g.salute

Alt er objekter

class Numeric
  def plus(x)
    self.+(x)
  end
end

y = 5.plus 6
# y is now equal to 11

class Ability
  include CanCan::Ability

  def initialize(user)
    if user.admin?
      can :manage, :all
    else
      can :read, :all
    end
  end
end

class Ability
  include CanCan::Ability

  def initialize(user)
    if user.admin?()
      can(:manage, :all)
    else
      can(:read, :all)
    end
  end
end

() yes, no, maybe

class SomeClass
  def initialize(value1)
    @value1 = value1
  end
 
  def value_printer(value2)
    lambda {puts "Value1: #{@value1}, Value2: #{value2}"}
  end
end
 
def caller(some_closure)
  some_closure.call
end
 
some_class = SomeClass.new(5)
printer = some_class.value_printer("some value")
 
caller(printer)

We got closure

Standardverdier som parameter

def sum(a = 1, b = 2, c = 3)
    a + b + c
end

sum 3, 3
=> 9

sum
=> 6

def tables(t = {})
    puts t
end

tables(absolute: true, round: true, precision: 2)
=> "{:absolute=>true, :round=>true, :precision=>2}"

Kun "false" og "nil" er false

x = true
y = x || 2
=> # y == 2

x = nil || y
=> # x == 2

# alt er som nevnt objekter
def nil.quack
    puts "quack quack" 
end
x = nil

x.quack
=> quack quack

Multippel returverdi

def foo(x)
 return x, x+1
end

a, b = foo(10)
#=> [10, 11]

class Publication
  attr_accessor :publisher
end

class Magazine < Publication
  attr_accessor :editor
end

m = Magazine.new
m.publisher = "Time Inc."

m.is_a? Magazine #=> true
m.is_a? Publication #=> true
m.class == Publication #=> false

Single inheritance

When I see a bird that walks like a duck and swims like a duck and quacks like a duck, I call that bird a duck

require_relative 'p036duck.rb'

def make_it_quack(duck)
  duck.quack
end

puts make_it_quack(Duck.new)
# Quack!
puts make_it_quack(DuckRecording.new)
# Quack!

def make_it_swim(duck)
  duck.swim
end

puts make_it_swim(Duck.new)
# Paddle paddle paddle...
puts make_it_swim(Goose.new)
# Splash splash splash...

How do I do that?

Ting man bør vite

https://docs.ruby-lang.org/en/2.4.0/

Løkker

a = [ "a", "b", "c" ]
a.each {|x| print x, " -- " }
# a -- b -- c --

a = [ "a", "b", "c" ]
a.each_index {|x| print x, " -- " }
# 0 -- 1 -- 2 --

h = { "a" => 100, "b" => 200 }
h.each {|key, value| puts "#{key} is #{value}" }
# a is 100
# b is 200

Funksjoner

def someMethod(value)
  puts "#{Time.now}: #{value}"
end

someMethod('log this with timestamp')
# 2017-05-30 22:17:19 +0200: log this with timestamp

Import av filer

load 'somefile.rb'
# Laster filen på nytt hver gang den blir kalt

require 'sinatra'
# Laster inn bibliotek/fil en gang

require_relative 'libs/my_helper.rb'
# Last inn en fil relativt til hvor filen som kaller den står

Variabler

# Global
$x = 10
defined? $x
# "global-variable"

# Lokale variabler
loopcounter = 10
_LoopCounter = 20

defined? loopcounter
# "local-variable"

# Constant (kinda)
Number = 123
NUMBER = 321
defined? NUMBER
# "constant"

# Class
@@total = 0
defined? @@total
# "class variable"

# Instance
@total = 10
defined? @total
# "instance-variable"

http://ruby-doc.org/core-2.4.0/doc/globals_rdoc.html

If/else

x = 1
if x > 2
   puts "x is greater than 2"
elsif x <= 2 and x!=0
   puts "x is 1"
else
   puts "I can't guess the number"
end

$debug = 1
print "debug\n" if $debug

x = 1 
unless x>2
   puts "x is less than 2"
 else
   puts "x is greater than 2"
end

$var =  1
print "1 -- Value is set\n" if $var
print "2 -- Value is set\n" unless $var

$var = false
print "3 -- Value is set\n" unless $var

$age =  5
case $age
when 0 .. 2
   puts "baby"
when 3 .. 6
   puts "little child"
when 7 .. 12
   puts "child"
when 13 .. 18
   puts "youth"
else
   puts "adult"
end

Sweet regex

IRB = Interactive Ruby Shell

#!/usr/bin/ruby

Gem

https://rubygems.org/

source 'https://rubygems.org'

ruby '2.4.1'

gem 'rails', '~> 5.0'

gem 'pg', '~> 0.20'

# Use Puma as the app server
gem 'puma', '~> 3.8'

gem 'haml', '~> 4.0'
gem 'redcarpet', '~> 3.4'
gem 'uglifier', '~> 3.1'
gem 'therubyracer', '~> 0.12'
gem 'pikaday-gem', '~> 1.4'
gem 'jquery-rails', '~> 4.3'
gem 'turbolinks', '~> 2.5'

group :production do
  # To enable features such as static asset serving and logging on Heroku
  gem 'rails_12factor', '~> 0.0'
end

# Use ActiveModel has_secure_password
gem 'bcrypt', '~> 3.1'

group :development, :test do
  # Call 'byebug' anywhere in the code to stop execution and get a debugger console
  gem 'byebug', '~> 9.0'
end

group :development do
  # Access an IRB console on exception pages or by using <%= console %> in views
  gem 'web-console', '~> 3.3'
  # Spring speeds up development by keeping your application running in the background.
  # Read more: https://github.com/rails/spring
  gem 'spring', '~> 2.0'
end

JRuby

https://jruby.org/

# This is the 'magical Java require line'.
require 'java'

# With the 'require' above, we can now refer to things that are part of the
# standard Java platform via their full paths.
frame = javax.swing.JFrame.new("Window") # Creating a Java JFrame
label = javax.swing.JLabel.new("Hello")

# We can transparently call Java methods on Java objects, just as if 
# they were defined in Ruby.
frame.add(label)  # Invoking the Java method 'add'.
frame.setDefaultCloseOperation(javax.swing.JFrame::EXIT_ON_CLOSE)
frame.pack
frame.setVisible(true)