argcheck.lua

-- depends on tostringall() https://gist.github.com/nefftd/11382819
-- see: line 15
do
  local err_fmt = "bad argument #%d to '%s' (%s expected, got %s)"
  
  local function checktypelist(t,a1,...)
    if a1 then
      return t == a1 or checktypelist(t,...)
    end
  end
  
  function argcheck(val,argn,...)
    local t = type(val)
    if not checktypelist(t,...) then
      local types = table.concat({tostringall(...)},'/')
      local fname = debug.getinfo(2,'n').name or 'unknown'
      argn = tonumber(argn) or 0
      error(err_fmt:format(argn,fname,types,t),3)
    end
  end
end