0-data-objects-recap.rb

# Quick data objects recap:

# There are 99 bottles of Indio in Cantina La Llorona.
# They cost $20.15 MXN each. The restaurant is currently closed.
number_of_bottles = 99         # Integer
name_of_the_bar = "La Llorona" # String
indio_price     = 20.15        # Float
is_it_open      = false        # boolean

# Cantina La Llorona has the following beers for sale:
# Leopoldina, Backbone, Dogma, Havana Dreams.
# Their prices are respectively:
#               0             1           2        3
beers_names  = ["Leopoldina", "Backbone", "Dogma", "Havana Dreams"]
beers_prices = [21.90       , 13.30     ,  44.90 , 18.90]

1-array-display-beer-prices.rb

# Write a program that prints beer prices.
#                 0              1  ...
beers_names  = ["Leopoldina", "Backbone", "Dogma", "Havana Dreams"]
beers_prices = [21.90       , 13.30     ,  44.90 , 18.90]

# associate objects by using =>
# key           value
beers_menu = {
  "Leopoldina" => 21.90,
  "Backbone" => 13.30,
  "Dogma" => 44.90,
  "Havana Dreams" => 18.90
}

# beers_menu = {
#   "Leopoldina" => { "price" => 21,90, "region" => "Chiapas" }
# }
# beers_menu["Leopoldina"] # => {"price" => 21,90, "region" => "Chiapas"}
# beers_menu["Leopoldina"]["price"]
# beers_menu["Leopoldina"]["region"]

beers_names.each_with_index do |beer_name, index|
  puts "#{beer_name} costs $#{beers_prices[index]} MXN"
end

2-array-and-hash-crud.rb

puts "====================="
puts "Array CRUD"
puts "====================="
#         0       1         2
array = ["Hank", "Bob", "Sheila"]

# Create
# << / #push / #append
array << "Uni"

# Read
# [index]
array[1]

# Update
# [index] =
array[1] = "Diana"

# Delete
# #delete_at(index)
array.delete_at(1)



puts "====================="
puts "Hash CRUD"
puts "====================="
# Hash literal
sao_paulo = {
  # key         value
  "name" => "São Paulo",
  "population" => 12_800_000,
  "main_monument" => "smog"
}
# "state" -> "São Paulo"

# Create
# [key] =
sao_paulo["state"] = "São Paulo"

# Read
# [key]
sao_paulo["name"]

# Update
# [key] = ----- for a key that exists
sao_paulo["population"] = 12_800_001

# Delete
# #delete(key)
sao_paulo.delete("main_monument")

3-hash-each.rb

paris = {
  :country => "France",
  :population => 2_211_000,
  :monument => "Pain au Chocolat"
}

sao_paulo = {
  :country => "Brazil",
  :population => 12_211_000,
  :monument => "smog"
}

# Let's iterate to output the info like this:
# The country is France
# The population is 2211000

# paris.each do |key, value|
# end
#                key        value
paris.each do |info_name, info_value|
  puts "The #{info_name} is #{info_value}"
end

4-playing-with-hashes.rb

paris = {
  "country" => "France",
  "population" => 2_211_000,
  "monument" => "Pain au Chocolat"
}

# What happens if I access a key that doesn't exist?
paris["beach"] => nil

# Checking the presence of a key
# paris.has_key?("beach")
paris.key?("beach")

# Return the keys of this hash
paris.keys # => ["country", "population", "monument"]

# Return the values of this hash
paris.values # => ["France", 2211000, "Pain au Chocolat"]

5-hash-to-symbol.rb

# Unconventional hashes (using strings as keys)
paris = {
  "country" => "France",
  "population" => 2_211_000
}

# Recommended in Ruby way (using symbols as keys)
# Symbols to represent identifiers:
paris = {
  :country => "France",
  :population => 2_211_000
}

# Shorthand hash literal (preferred):
paris = {
  country: "France",
  population: 2_211_000
}

6-hash-last-argument.rb

# Accepts 2 or 3 arguments
def tag(tag_name, content, attributes = {})
  attributes_string = ""
  attributes.each do |attr_name, attr_value|
    attributes_string += " #{attr_name}='#{attr_value}'"
  end
  return "<#{tag_name}#{attributes_string}>#{content}</#{tag_name}>"
end

puts tag("h1", "Hello world", { class: "bold" })
puts tag("h1", "Hello world", class: "bold")

puts tag("a", "Le Wagon", { href: "http://lewagon.org", class: "btn" })
puts tag("a", "Le Wagon", href: "http://lewagon.org", class: "btn")