Lua中单例的使用

--test
local config = {}

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

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

function config:Func()
  self.index = self.index or 0
  self.index = self.index + 1
  print("self.index",self.index)
end

return config

--test2
local test = require "test"
local test1 = test:Instance()
test1:Func()
local test2 = test:Instance()
test2:Func()
local test3 = test:new()
test3:Func()
if test1 == test2 then
  print("test1 == test2")
else
  print("test1 ~= test2")
end
if test1 == test3 then
  print("test1 == test3")
else
  print("test1 ~= test3")
end

--output：
--self.index    1
--self.index    2
--self.index    1
--test1 == test2
--test1 ~= test3