Ruby - Enumerator

enumerator.rb

def print_enum(enum)
  puts enum
  puts enum.inspect
end

# Example: 1
enum = %w(foo bar).each
print_enum(enum)

3.times { puts enum.next } rescue nil

print_enum(enum)

# Example: 2
enum2 = %w(a b c d e).each
print_enum(enum2)

enum2.each_with_object('letter') do |item, obj|
  puts "#{obj}: #{item}"
end

while e = enum2.next
  puts e
end

enumerator_2.rb

##
# Enumerator#lazy
##
enum =
  { name: 'Tiago Guedes', email: '[email protected]' }
    .lazy
    .map { |(key, value)| puts key; [key, value] }
    .find { |e| e[1] == 'Tiago Guedes' }
#=> name
puts enum[1] #=> Tiago Guedes

##
# Enumerator#yield
##
enum = Enumerator.new do |e|
  map_find =
    { name: 'Tiago Guedes', email: '[email protected]' }
      .map { |(key, value)| puts key; [key, value] }
      .find { |e| e[1] == 'Tiago Guedes' }
  e.yield map_find
end
#=> name
#=> email
enum.each { |e| puts e[1] } #=> Tiago Guedes

enumerator_chunk.rb

[1, 3, 2, 4, 5, 6].chunk { |e| e.even? }.each { |result, array| print array; print ',' } #=> [1, 3],[2, 4],[5],[6],=> nil
'foo bar foobar'.split.sort.chunk { |e| e.ord }.each { |result, array| print "#{array.first[0]} - #{array.length}"; print ',' } #=> b - 1,f - 2,=> nil