python闭包

Posted 2022-01-31 w-y-c

闭包

• # 第一版： 没有保证数据的安全
  # l1 = []  #全局变量
  # def make_average(price):
  #     l1.append(price)
  #     total = sum(l1)
  #     return total/len(l1)
  # print(make_average(100000))
  # print(make_average(110000))
  # print(make_average(120000))
  # '''
  # 有很多代码....
  # '''
  # l1.append(666)
  # print(make_average(90000))
  # 第二版：
  # 每次执行l1是空的。
  # def make_average(price):
  #     l1 = []
  #     l1.append(price)
  #     total = sum(l1)
  #     return total/len(l1)
  # print(make_average(100000))
  # print(make_average(110000))
  # print(make_average(120000))
  # 为了保证数据的安全，闭包
  def make_average():
      l1 = []
      def average(price):
          l1.append(price)
          total = sum(l1)
          return total/len(l1)
      return average
  avg = make_average()
  # print(avg)
  print(avg(100000))
  print(avg(110000))
  print(avg(120000))
  # print(globals())
  #
  # def make_average():
  #
  #     count = 1
  #     def average():
  #         nonlocal count
  #         count += 1
  #         return count
  #     return average
  # avg = make_average()
  # # print(avg)
  # print(avg())
  # print(avg())
  # print(avg())
  # print(avg())
  # 例一：
  # def wrapper():
  #     a = 1
  #     def inner():
  #         print(a)
  #     return inner
  # ret = wrapper()
  # 
  # # 例二：
  # a = 2
  # def wrapper():
  #     def inner():
  #         print(a)
  #     return inner
  # ret = wrapper()
  # 
  # # 例三：
  # 
  def wrapper(a,b):
      '''
      :param a: 2
      :param b: 3
      :return:
      '''
      name = 'alex'
      def inner():
          print(a)
          print(b)
          name = 'alex'
      return inner
  a = 2
  b = 3
  ret = wrapper(a, b)
  # 业哥 不是
  # 其他人 都说是
  # 判断一个函数是不是闭包 == 闭包函数有没有自由变量
  print(ret.__code__.co_freevars)
  # 了解
  print(ret.__code__.co_varnames)  # 函数中的局部变量
  # 闭包的应用：
  # 1，保证数据的安全。
  # 2，装饰器的本质。