class Rake::ExtensionTask

def fake_rb(platform, version)
  <<-FAKE_RB
    class Object
      remove_const :RUBY_PLATFORM
      remove_const :RUBY_VERSION
      remove_const :RUBY_DESCRIPTION if defined?(RUBY_DESCRIPTION)
      RUBY_PLATFORM = "#{platform}"
      RUBY_VERSION = "#{version}"
      RUBY_DESCRIPTION = "ruby \#{RUBY_VERSION} (\#{RUBY_RELEASE_DATE}) [\#{RUBY_PLATFORM}]"
    end
    if RUBY_PLATFORM =~ /mswin|bccwin|mingw/
      class File
        remove_const :ALT_SEPARATOR
        ALT_SEPARATOR = "\\\\"
      end
    end
    posthook = proc do
      $ruby = "#{Gem.ruby}"
      untrace_var(:$ruby, posthook)
    end
    trace_var(:$ruby, posthook)
_RB
end