undantagshantering_1.rb

def list_files_in_dir
  files = Dir.glob('*.*')
  files.each_with_index do |file, i|
    puts "#{i + 1}: #{file}"
  end
end

def ask_for_filename
  print 'Enter name  of file to open '
  filename = gets.chomp
  return filename
end

def display_file(filename:)
  if File.exists?(filename)
    File.readlines(filename).each_with_index do |line, i| 
      puts "#{i + 1}: #{line}"
    end
  else
    puts "Cannot find file #{filename}"
    puts "Please try again"
    puts "These files are available:"
    list_files_in_dir
    filename = ask_for_filename
    display_file(filename: filename)
  end
  
  # Exceptions should be EXCEPTIONAL
  # begin
  #   File.readlines(filename).each_with_index do |line, i|
  #     puts "#{i + 1}: #{line}"
  #   end
  # rescue Errno::ENOENT => error
  #   puts "Cannot find file #{filename}"
  #   puts "Please try again"
  #   puts "These files are available:"
  #   list_files_in_dir
  #   filename = ask_for_filename
  #   display_file(filename: filename)
  # end
end

list_files_in_dir
filename = ask_for_filename
display_file(filename: filename)

undantagshantering_2.rb

class CountdownTooShortError < Exception ; end

def countdown(from:)
  raise TypeError, 'from must be a Fixnum' unless from.is_a? Fixnum
  raise ArgumentError, 'from must not be negative' if from < 0
  raise CountdownTooShortError, 'can not count down from zero' if from == 0
  current = from
  numbers = []
  while current >= 0
    numbers << current
    current -= 1
  end
  return numbers
end

def audio_countdown
  begin
    countdown(from: 0).each do |number|
      system("say #{number}")
      sleep 1
    end
  rescue ArgumentError => e
    system("say Can not initiate countdown")
  rescue CountdownTooShortError => e
    system("say well, shiiiit!")
    system("say boom!")
  end
end

audio_countdown