ruby TkPackage can't find package BWidget 之解决办法

一个特别短的ruby/tk代码:

require 'tkextlib\iwidgets'
require 'tkextlib\bwidget'

x = 0
101.times {|i| x+=i}
Tk.messageBox(:type=>:ok,:title=>"win",:message=>"total 100 is #{x}")

但是运行提示出错：

/usr/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55:in `require': cannot load such file -- tkextlib\iwidgets (LoadError)
	from /usr/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55:in `require'
	from 1945.rb:1:in `<main>'

这段代码原来是windows下写的，首先发现路径分隔符在linux需要用/。windows下估计/和\都可以吧？！然后接着运行，原来的错误木有了，新的错误出现鸟：

/usr/lib/ruby/2.1.0/tk/package.rb:86:in `rescue in require': TkPackage can't find package BWidget (RuntimeError)
	from /usr/lib/ruby/2.1.0/tk/package.rb:83:in `require'
	from /usr/lib/ruby/2.1.0/tkextlib/bwidget.rb:16:in `<top (required)>'
	from /usr/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55:in `require'
	from /usr/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55:in `require'
	from 1945.rb:2:in `<main>'

提示找不到BWidget包，遂locate之，发现头文件啥的都是有的啊：

/usr/lib/ruby/2.1.0/tkextlib/bwidget
/usr/lib/ruby/2.1.0/tkextlib/bwidget.rb
/usr/lib/ruby/2.1.0/tkextlib/bwidget/arrowbutton.rb
/usr/lib/ruby/2.1.0/tkextlib/bwidget/bitmap.rb
/usr/lib/ruby/2.1.0/tkextlib/bwidget/button.rb
/usr/lib/ruby/2.1.0/tkextlib/bwidget/buttonbox.rb
/usr/lib/ruby/2.1.0/tkextlib/bwidget/combobox.rb
/usr/lib/ruby/2.1.0/tkextlib/bwidget/dialog.rb
/usr/lib/ruby/2.1.0/tkextlib/bwidget/dragsite.rb
/usr/lib/ruby/2.1.0/tkextlib/bwidget/dropsite.rb
/usr/lib/ruby/2.1.0/tkextlib/bwidget/dynamichelp.rb
/usr/lib/ruby/2.1.0/tkextlib/bwidget/entry.rb
/usr/lib/ruby/2.1.0/tkextlib/bwidget/label.rb
/usr/lib/ruby/2.1.0/tkextlib/bwidget/labelentry.rb
/usr/lib/ruby/2.1.0/tkextlib/bwidget/labelframe.rb
/usr/lib/ruby/2.1.0/tkextlib/bwidget/listbox.rb
/usr/lib/ruby/2.1.0/tkextlib/bwidget/mainframe.rb
/usr/lib/ruby/2.1.0/tkextlib/bwidget/messagedlg.rb
/usr/lib/ruby/2.1.0/tkextlib/bwidget/notebook.rb
/usr/lib/ruby/2.1.0/tkextlib/bwidget/pagesmanager.rb
/usr/lib/ruby/2.1.0/tkextlib/bwidget/panedwindow.rb
/usr/lib/ruby/2.1.0/tkextlib/bwidget/panelframe.rb
/usr/lib/ruby/2.1.0/tkextlib/bwidget/passwddlg.rb
/usr/lib/ruby/2.1.0/tkextlib/bwidget/progressbar.rb
/usr/lib/ruby/2.1.0/tkextlib/bwidget/progressdlg.rb
/usr/lib/ruby/2.1.0/tkextlib/bwidget/scrollableframe.rb
/usr/lib/ruby/2.1.0/tkextlib/bwidget/scrolledwindow.rb
/usr/lib/ruby/2.1.0/tkextlib/bwidget/scrollview.rb
/usr/lib/ruby/2.1.0/tkextlib/bwidget/selectcolor.rb
/usr/lib/ruby/2.1.0/tkextlib/bwidget/selectfont.rb
/usr/lib/ruby/2.1.0/tkextlib/bwidget/separator.rb
/usr/lib/ruby/2.1.0/tkextlib/bwidget/setup.rb
/usr/lib/ruby/2.1.0/tkextlib/bwidget/spinbox.rb
/usr/lib/ruby/2.1.0/tkextlib/bwidget/statusbar.rb
/usr/lib/ruby/2.1.0/tkextlib/bwidget/titleframe.rb
/usr/lib/ruby/2.1.0/tkextlib/bwidget/tree.rb
/usr/lib/ruby/2.1.0/tkextlib/bwidget/widget.rb
/usr/lib/x86_64-linux-gnu/deja-dup/libwidgets.so
/usr/lib/x86_64-linux-gnu/qt5/qml/QtQuick/PrivateWidgets/libwidgetsplugin.so

难道是库文件没有?于是乎用 sudo apt-get install bwidget安装，接着运行，这个世界清净啦: