String interpolation in Lua

string_interpolation.lua

--- Add support for interpolation into string using %.
--
-- Examples:
--   "Hi, %s!" % 'Mindy'  --> Hi, Mindy!
--   "Hi, ${name}!" % {name = 'Mindy'}  --> Hi, Mindy!
getmetatable('').__mod = function(str, args)
  if type(args) ~= 'table' then
    args = { args }
  end
  return str:format(unpack(args)):gsub('($%b{})', function(placeholder)
    return args[placeholder:sub(3, -2)] or placeholder
  end)
end