nelantone

# Example 1
# to see the object ids when we have a variable shadowing

a = [1, 2, 3]

a.object_id # => 1960

a.map! do |a| 
  p a.object_id
  a + 1

nelantone

a = ['a','b', 'c']

a.each do |b| 
   b.upcase!
   a = ['reassign?']
end

p a # => ['reassign?'] yes! Reassignment

nelantone

b = ['a','b', 'c']

b.each do |b| 
   b.upcase!
   b = ['reassign?']
end

p b # => ['A','B','C'] nope! No reassignment

nelantone

a = ['a','b', 'c']
 
a.each do |b| 
  b.upcase! # upcase is not an array method so we use `b` instead a[1] = 'd'
  a[1] = 'd'
end

p a # => ['Ad','d','Cd']

nelantone

on line 1 we initialize the variable assiging it to a string collection.

on line 4 we call each method on a object assigned to the object collection pointing to a.

on line 5 as we the variable is shadowing each specific objects 'a','b', 'c' will be modified to upcase(if we will try to call a.upcase! out of the block we will raise an exception).

on line 6 we modify again each object, but the array is the same, so we can't modify the array

on line 9 the return value is => ['Ad','Bd','Cd'] because we modify each object inside the collection but not the array the concept of variable shadowing is also applied in case will not be applied we will have a => ['A','d','C']

nelantone

greet_var = "Hi there"

loop do |greet_var| # |greet_var| block parameter
  greet_var = "What's up from the block" # inner scope `greet_var`
end

greet_var # => "Hi there" # the outer sope variable is protected

nelantone

a = ['a','b', 'c']

a.each do |a| 
   a.upcase!
   a[1] = 'd'
end

p a

nelantone

str = "hello"
str.is_a?(Object)
str.class

class String
  def star
    self + " *"
  end
end

nelantone

class Cat
  attr_reader :color, :breed
  attr_accessor :name

  def initialize(color, breed, hungry)
    @color = color
    @breed = breed
    @hungry = true
  end

nelantone

def fav_foods
  food_array = []
  3.times do 
    puts 'please choose your favorite food'
    food_array << gets.chomp
  end

  puts "Your favorite foods are #{food_array}.join(', ')."

  p food_array