Hash & Symbols

hash.rb

students =     [ "Peter", "Mary", "George", "Emma" ]
student_ages = [ 24     , 25    , 22      ,  20    ]

# "Peter is 24 yo!"
# "Mary is 25 yo!"
# ...

students.each_with_index do |student, index|
  puts "#{student} is #{student_ages[index]}"
end

student_ages = {
  "Peter" => 24,
  "Mary" => 25,
  "George" => 22
}

puts student_ages["Peter"]`

json.rb

require 'json'
require 'open-uri'

puts "Give me a username:"
nickname = gets.chomp

serialized_json = open("https://api.github.com/users/#{nickname}").read
user_hash = JSON.parse(serialized_json)

puts "#{user_hash["name"]} has #{user_hash["public_repos"]} public repos!"

paris.rb

students =     [ "Peter", "Mary", "George", "Emma" ]

# paris = {
#   "population" => 2211000,
#   "country" => "France",
# }

# CRUD
# Array
# C. students.push("mario") / <<
# R. students[1]
# U. students[2] = "Luca"
# D. students.delete("Mary") / .delete_at(1)

# Hash
# C./U. paris["monument"] = "Tour Eiffel"
# R. paris["population"]
# D. paris.delete("population")

paris = [
  ["population", 2211000],
  ["country", "France"]
]
puts paris[1][1]

puts paris["country"]

puts paris.key?("country")
puts paris.key?("house")


paris.each do |key, value|
  puts "#{key} is #{value}!"
end

# paris.each do |object|
#   p object
# end

symbol.rb

paris = {
  "country" => "France",
  "population" => 2211000
}

paris = {
  :country => "France",
  :population => 2211000
}

paris = {
  country: "France",
  population: 2211000
}

# Text data => String
"Sebastien Saunier"
"seb@lewagon.org"
"ruby on Rails"
"Paris"

# Text identifiers => Symbol
:fullname
:email
:skill
:city

tag.rb

tag("h1", "Hello world", attr = {})

<h1 class="container" id="title" style="color:red;">
  Hello world
</h1>


def tag(tag_name, content = "", attr = {})
  # {} -> [] .map
  attributes = attr.map { |key, value| "#{key.to_s}: #{value}" }.join

  return "<#{tag_name} #{attributes.join}>#{content}</#{tag_name}>"  
end

tag("h1", "Hello world")
tag("h1", "Hello world", class: "container", id: "title", style: "color:red;")

<h1 class="container" id="title" style="color:red;">
  Hello world
</h1>