Singleton = {}
function Singleton:new(o)
    o = o or {}
    setmetatable(o,self)
    self.__index = self
    return o
end

function Singleton:Instance()
    if self.instance == nil then
        self.instance = self:new()
    end
    return self.instance
end


s1 = Singleton:Instance()

s2 = Singleton:Instance()

if s1 == s2 then
    print("两个对象是相同的实例")
end