在lua中创建类和对象

Account = {balance = 10}
function Account:withdraw (v)
	self.balance = self.balance - v
end

function Account:deposit (v)
	self.balance = self.balance + v
end

function Account:create()
	local o = {}
	setmetatable(o, self)
	self.__index = self
	return o
end

a = Account:create()
--重写基类方法
function a:deposit(v)
	print("hello world")
end

print(a.balance)
a:deposit(100)