calcutator prompt for awesome wm

calc.lua

-- Insert in your rc.lua to globalkeys (may be after mod+x) defining
-- In awesome 4.0 :
   awful.key({ modkey }, "c",
      function ()
         awful.prompt.run {
            prompt       = "Calculate: ",
            textbox      = awful.screen.focused().mypromptbox.widget,
            exe_callback = function (text)
               awful.spawn.easy_async(
                  "python -c \"from math import * ; print(" .. text .. ")\"",
                  function(stdout, stderr, exitreason, exitcode)
                     naughty.notify({
                           text = 'Result: ' .. string.sub(stdout, 1, -2),
                           position = "top_left",
                           timeout = 5
                     })
                  end)
            end
         }
      end,
      {description = "inline calculator", group = "awesome"}),
  
-- In awesome 3.5
   awful.key({ modkey }, "c",
      function ()
	 awful.prompt.run({ prompt = "Calculate: " },
	    mypromptbox[mouse.screen].widget,
	    function (text)
	       naughty.notify({
		     text = 'Result: ' .. awful.util.pread("python -c \"from math import * ; print(" .. text .. ",end='')\""),
		     position = "top_left",
		     timeout = 5
	       })
	 end)
   end),