Ruby Day 3 Livecode - Iterators and Blocks

1-recap-array.rb

musicians = ['David Gilmour', 'Roger Waters', 'Richard Wright', 'Nick Mason']
#                   0             1                2                3
puts musicians.length

# Array CRUD
# Create
# musicians.push("Steven Wilson")
musicians << "Steven Wilson"
p musicians

# Read
p musicians[2]

# Update
musicians[2] = "James LaBrie"
p musicians[2]

# Delete
musicians.delete_at(1)
musicians.delete("Nick Mason")
p musicians

2-recap-range.rb

# Range
# .. ...

# .. 2 dots
array_1_to_10 = (1..10).to_a
p array_1_to_10

# ... 3 dots
array_1_to_9 (1...10).to_a
p array_1_to_9

3-recap-for.rb

musicians = ['David Gilmour', 'Roger Waters', 'Richard Wright', 'Nick Mason']

# Let's loop with the array
for musician in musicians
  p musician
end

# Let's loop with just the indexes
for index in 0...(musicians.length)
  p musicians[index]
end

# Now forget about for and focus on iterators! =)

4-each-musicians.rb

musicians = [
  'David Gilmour',
  'Roger Waters',
  'Richard Wright',
  'Nick Mason'
]

# Let's say hi to them
musicians.each do |musician|
  p "Hi, #{musician}!"
end

# Let's list with numbers
musicians.each_with_index do |musician, index|
  p "#{index + 1}. #{musician}"
end

# Let's list with numbers (but without each_with_index)
# PS.: this is just for exercise. Prefer the above.
counter = 1
musicians.each do |musician|
  p "#{counter}. #{musician}"
  counter += 1
end

5-map-musicians.rb

musicians = [
  'David Gilmour',
  'Roger Waters',
  'Richard Wright',
  'Nick Mason'
]

# Let's map this to a new array:
# - upcased array
upcased_musicians = musicians.map do |musician|
  musician.upcase
end

p musicians
p upcased_musicians

# - first names array
first_names_array = musicians.map do |musician|
  musician.split.first
end

p first_names_array

6-count-musicians.rb

musicians = [
  'David Gilmour',
  'Roger Waters',
  'Richard Wright',
  'Nick Mason'
]

# Let's count the musicians starting with "R"
starting_with_r_count = musicians.count do |musician|
  musician.start_with?("R")
end
p starting_with_r_count


# Now let's do it with just #each
# PS.: The above is ofc still preferred
counter = 0
musicians.each do |musician|
  if musician.start_with?("R")
    counter += 1
  end
end
p counter

7-select-musicians.rb

musicians = [
  'David Gilmour',
  'Roger Waters',
  'Richard Wright',
  'Nick Mason'
]

# Select (filter) musicians starting with "R"
musicians_starting_with_r = musicians.select do |musician|
  musician.start_with?("R")
end
p musicians_starting_with_r

# Reject musicians starting with "R"
musicians_not_starting_with_r = musicians.reject do |musician|
  musician.start_with?("R")
end
p musicians_not_starting_with_r

8-blocks-timer.rb

# Let's write a benchmark tool
def timer
  start_time = Time.now

  yield

  end_time = Time.now
  puts "The task took #{end_time - start_time} seconds"
end

# Calling our timer method
timer do
  puts "Starting task 1..."
  sleep 2
  puts "Finished task 1!"
end

# Calling our timer method (with a different block of code)
timer do
  puts "Starting task 2..."
  sleep 1
  puts "Finished task 2!"
end

9-custom-greeting.rb

def stylize_name(first_name, last_name)
  full_name = "#{first_name.capitalize} #{last_name.upcase}"
  yield(full_name)
end

# We want to customize this stylize_name message with a block.
message = stylize_name("ringo", "starr") do |name|
  "Hey, #{name}! Learn to play!"
end
puts message