pry--pry/lib/pry/commands/gem_install.rb

class Pry
  Pry::Commands.create_command "gem-install" do |gem|
    group 'Gems'
    description "Install a gem and refresh the gem cache."
    command_options :argument_required => true

    banner <<-BANNER
      Usage: gem-install GEM_NAME

      Installs the given gem and refreshes the gem cache so that you can immediately 'require GEM_FILE'
    BANNER

    def setup
      require 'rubygems/dependency_installer' unless defined? Gem::DependencyInstaller
    end

    def process(gem)
      begin
        destination = File.writable?(Gem.dir) ? Gem.dir : Gem.user_dir
        installer = Gem::DependencyInstaller.new :install_dir => destination
        installer.install gem
      rescue Errno::EACCES
        raise CommandError, "Insufficient permissions to install `#{text.green gem}`."
      rescue Gem::GemNotFoundException
        raise CommandError, "Gem `#{text.green gem}` not found."
      else
        Gem.refresh
        output.puts "Gem `#{text.green gem}` installed."
        require gem
      end
    end
  end
end