vincentbernat.i3wm-configuration/rc/debug.lua

local colors = {
  header = theme.fg_widget_clock,
  count  = theme.fg_widget_label,
  index  = theme.fg_widget_label,
  name   = theme.fg_widget_value_important,
}

local function client_info()
    local v = ""

    -- object
    local c = client.focus
    v = v .. tostring(c)

    -- geometry
    local cc = c:geometry()
    local signx = (cc.x > 0 and "+") or ""
    local signy = (cc.y > 0 and "+") or ""
    v = v .. " @ " .. cc.width .. 'x' .. cc.height .. signx .. cc.x .. signy .. cc.y .. "\n\n"

    local inf = {
        "name", "icon_name", "type", "class", "role", "instance", "pid",
        "skip_taskbar", "id", "group_window", "leader_id", "machine",
        "screen", "hidden", "minimized", "size_hints_honor", "titlebar", "urgent",
        "focus", "opacity", "ontop", "above", "below", "fullscreen", "transient_for",
	"maximixed_horizontal", "maximixed_vertical", "sticky", "modal", "focusable"
    }

    for i = 1, #inf do
        v = v .. string.format('%2s: <span color="%s">%-20s</span> = <span color="%s">%s</span>\n',
			       i,
			       beautiful.fg_widget_label, inf[i],
			       beautiful.fg_widget_value, tostring(c[inf[i]]))
    end

    naughty.notify{ text = string.format('<span font="Terminus 8">%s</span>', v:sub(1,#v-1)),
		    timeout = 0, margin = 10, screen = c.screen }
end

local function dbg_get(var, depth, indent)
  local a = ""
  local text = ""
  local name = ""
  local vtype = type(var)
  local vstring = tostring(var)

  if vtype == "table" or vtype == "userdata" then
    if vtype == "userdata" then var = getmetatable(var) end
    -- element count and longest key
    local count = 0
    local longest_key = 3
    for k,v in pairs(var) do
      count = count + 1
      longest_key = math.max(#tostring(k), longest_key)
    end
    text = text .. vstring .. " <span color='"..colors.count.."'>#" .. count .. "</span>"
    -- descend a table
    if depth > 0 then
      -- sort keys FIXME: messes up sorting number
      local sorted = {}
      for k, v in pairs(var) do table.insert(sorted, { k, v }) end
      table.sort(sorted, function(a, b) return tostring(a[1]) < tostring(b[1]) end)
      -- go through elements
      for _, p in ipairs(sorted) do
        local key = p[1]; local value = p[2]
        -- don't descend _M
        local d; if key ~= "_M" then d = depth - 1 else d = 0 end
        -- get content and add to output
        local content = dbg_get(value, d, indent + longest_key + 1)
        text = text .. '\n' .. string.rep(" ", indent) ..
               string.format("<span color='"..colors.index.."'>%-"..longest_key.."s</span> %s",
                             tostring(key), content)
      end
    end
  else
    if vtype == "tag" or vtype == "client" then
      name = " [<span color='"..colors.name.."'>" .. var.name:sub(1,10) .. "</span>]"
    end
    text = text .. vstring .. name or ""
  end

  return text
end

function dbg(...)
   local num = table.maxn(arg)
   local text = "<span color='"..colors.header.."'>dbg</span> <span color='"..colors.count.."'>#"..num.."</span>"
   local depth = 2
   local clients = 0

   for i = 1, num do
      local desc = dbg_get(arg[i], depth, 3)
      text = text .. string.format("\n<span color='"..colors.index.."'>%2d</span> %s", i, desc)
      if type(arg[i]) == "client" then
	 client_info(arg[i])
	 clients = clients + 1
      end
   end

   -- Display only if we don't have only clients to be displayed
   if clients ~= num then
      naughty.notify{ text = text, timeout = 0, hover_timeout = 0.05, screen = screen.count() }
   end
end