Generate a new instance in lua

instance.lua

local MyClass = {}
MyClass.__index = MyClass

setmetatable(MyClass, {
  __call = function (cls, ...)
  return cls.new(...)
  end,
})

function MyClass.new(init)
  local self = setmetatable(init, MyClass)
  return self
end

-- the : syntax here causes a "self" arg to be implicitly added before any other args
function MyClass:set_value(newval)
  self.value = newval
end

function MyClass:get_value()
  return self.value
end

local instance = MyClass.new({
  node = true,
  npm = true
})
-- do stuff with instance...

for k, v in pairs(instance) do
  print(k, v)
end