07_refactoring.rb

# *One-line conditions*
# use them *only* when you have one condition (and no `elsif` or `else`)

# 1. One-line if statement

names = ["gabriele", "mariana", "shannon"]

if names.include?("shannon")
  puts "Shannon is with us today!"
end
# will become
puts "Shannon is with us today!" if names.include?("shannon")

# 2. One-line unless statement

movies = {
  pulp_fiction: 5,
  memento: 4
}

unless movies[:pulp_fiction] != 5
  puts "Pulp Fiction is a top movie!"
end
# will become
puts "Pulp Fiction is a top movie!" unless movies[:pulp_fiction] != 5

##################

# *Ternary operator* (one line if-else statement)
# also here use it *only* when you have one if and one else condition!

names = ["gabriele", "mariana", "shannon"]

if names.include?("shannon")
  puts "Shannon is with us today!"
else
  puts "Shannon is always too busy :("
end
# will become
puts names.include?("shannon") ? "Shannon is with us today!" : "Shannon is always too busy :("

###################

# *Case statement* (a.k.a switch statement)
# use it when you have a lot of elsif conditions!

puts "Where are you from?"
country = gets.chomp

if country == "England"
  puts "Hello!"
elsif country == "Italy"
  puts "Ciao!"
elsif country == "Portugal"
  puts "Olá!"
elsif country == "Germany"
  puts "Halo!"
else
  puts "👋"
end
# will become
case country
  when "England"
    puts "Hello!"
  when "Italy"
    puts "Ciao!"
  when "Portugal"
    puts "Olà!"
  when "Germany"
    puts "Halo!"
  else
    puts "👋"
end
# or, even shorter:
case country
  when "England" then puts "Hello!"
  when "Italy" then puts "Ciao!"
  when "Portugal" then puts "Olà!"
  when "Germany" then puts "Halo!"
  else puts "👋"
end

#################

# *Conditional assignment*
# you assign a variable *only* if the variable is not already defined

beatles = {
  singer: "John",
  guitarist: "Paul",
  bassist: "George",
}

beatles[:singer] ||= "Mick" # will not be assigned here! The singer already exists
beatles[:drummer] ||= "Ringo" # it will assign it here, because the drummer doesn't exist yet!

beatles.each do |role, name|
  puts "#{name} is the #{role}"
end

##################

# *Implicit return*
# never use the return keyword to return the last line of your method (the return is automatic!)

def reverse_and_upcase_name(name)
  reversed_name = name.reverse
  reversed_name.upcase # no return here!
end

my_name = reverse_and_upcase_name("gabriele")
puts my_name

##################

# *One-line blocks*

# Ranges and arrays
numbers = (1..100).to_a # `1..100` is a range, `to_a` makes it an array with all the elements in that range!
# other ways:
numbers = 1.upto(100).to_a
numbers = 100.downto(1).to_a
# also with letters!
letters = "G".upto("Z").to_a

numbers.each do |n|
  if n % 2 == 0
    puts n
  end
end
# will become
numbers.each { |n| puts n if n % 2 == 0 }

#######################

# *Other methods*

# `respond_to?`
# use it to check if a method can be applied on a specific element (not very common, just test the method manually!)
[1, 2, 3].respond_to?(:push) # => true, I can apply `push` on an array
[1, 2, 3].respond_to?(:to_sym) # => false, `to_sym` can't be applied on an array
"hello".respond_to?(:reverse) # => true
"hello".respond_to?(:delete_at) # => false

# The `<<` operator
# on an array:
array = [1, 2, 3]
array.push(4)
array << 5 # same as `array.push(5)`
puts array
# on a string:
string = "hello"
string += " there!"
string << " how are you doing?" # same as `string += " how are you doing?"`
puts string

# Interpolation (we already know it!)
name = "gabriele"
puts "My name reversed is " + name.reverse # DON'T use this, use interpolation!
puts "My name reversed is #{name.reverse}"

# `times`
# use it to repeating something n times
3.times { puts "I'm a refactoring master!" }