helpers: properly handle magic characters

TODO

@@ -5,11 +5,11 @@
 
 
 * Vicious
+** TODO Consider commiting power drain support to bat.lua
+** TODO Try replacing dio.lua with io.lua
+*** TODO First io.lua should grab data for all devices
 ** TODO Document contrib widgets in contrib/README
 ** TODO Consider multigraph, graph stacking, support
-** TODO Consider including this code in format helper
-   - return format and format:gsub("${[^}]+}", "")
-   - Note: We should then also replace just $1/$2...
 ** TODO Complete the hddtemp fix
    - In certain setups regexp does not match all devices
      - The regexp catches the first device name, but last stats

helpers.lua

@@ -9,6 +9,7 @@
 
 -- {{{ Grab environment
 local pairs = pairs
+local tonumber = tonumber
 local io = { open = io.open }
 local setmetatable = setmetatable
 local getmetatable = getmetatable
@@ -53,7 +54,9 @@ end
 -- {{{ Format a string with args
 function format(format, args)
     for var, val in pairs(args) do
-        format = format:gsub("$" .. var, val)
+        format = format:gsub("$" .. (tonumber(var) and var or
+            var:gsub("[-+?*]", function(i) return "%"..i end)),
+        val)
     end
 
     return format