A Ruby script that installs all gems it is missing

So you want your Ruby script to install missing gems instead of dying? Take this method:

def installing_missing_gems(&block)
  yield
rescue LoadError => e
  gem_name = e.message.split('--').last.strip
  install_command = 'gem install ' + gem_name
  
  # install missing gem
  puts 'Probably missing gem: ' + gem_name
  print 'Auto-install it? [yN] '
  gets.strip =~ /y/i or exit(1)
  system(install_command) or exit(1)
  
  # retry
  Gem.clear_paths
  puts 'Trying again ...'
  require gem_name
  retry
end

Use it like this:

installing_missing_gems do
  require 'thor'
  require 'nokogiri'
  # some code using those gems
end