lib/core.lua

core = {}

core.update = function (test)
  return 'update: ' .. test
end

core.install = function()
  print('install')
end

local cli = {
  ["update"] = { [1] = ""; usage = ""};
  ["install"] = { [1] = ""; usage = ""};
  validate = function(self, cmd, ...)
    if #arg < #self[cmd] then
      error({code = 100; message = "Not enough arguments."})
    end
    return true
  end;
  info = function(self, cmd, ...)
    local func = nil
    status, err = pcall(self.validate, self, cmd, unpack(arg or {}))
    if status then func = core[cmd] else func = function (...) print(err.code, err.message) end end
    return func, arg
  end;
}

local arg0 = 'update'
local args = {}
local func, args = cli:info(arg0, unpack(args))

print(arg0, ': ', func,': ',args, ' :: ', func(unpack(args)))
print("\ndone.")