process_options

# File lib/rubygems/installer.rb, line 635
  def process_options # :nodoc:
    @options = {
      :bin_dir      => nil,
      :env_shebang  => false,
      :force        => false,
      :only_install_dir => false,
      :post_install_message => true
    }.merge options

    @env_shebang         = options[:env_shebang]
    @force               = options[:force]
    @install_dir         = options[:install_dir]
    @gem_home            = options[:install_dir] || Gem.dir
    @ignore_dependencies = options[:ignore_dependencies]
    @format_executable   = options[:format_executable]
    @wrappers            = options[:wrappers]
    @only_install_dir    = options[:only_install_dir]

    # If the user has asked for the gem to be installed in a directory that is
    # the system gem directory, then use the system bin directory, else create
    # (or use) a new bin dir under the gem_home.
    @bin_dir             = options[:bin_dir] || Gem.bindir(gem_home)
    @development         = options[:development]
    @build_root          = options[:build_root]

    @build_args          = options[:build_args] || Gem::Command.build_args

    unless @build_root.nil?
      require 'pathname'
      @build_root = Pathname.new(@build_root).expand_path
      @bin_dir = File.join(@build_root, options[:bin_dir] || Gem.bindir(@gem_home))
      @gem_home = File.join(@build_root, @gem_home)
      alert_warning "You build with buildroot.\n  Build root: #{@build_root}\n  Bin dir: #{@bin_dir}\n  Gem home: #{@gem_home}"
    end
  end