序列化shelve模块

 

import shelve

set1 = {'a', 'b', 'c', 'd'}
f1 = shelve.open("sh_file.txt")
f1['key'] = set1
f1.close()


f2 = shelve.open("sh_file.txt")
print(f2['key'])
f2.close()

 借助参数writeback   shelve模块可以将我们对被序列化的类型 的改动  及时感知并记录下来

import shelve

lst = ['a', 'b', 'c', 'e']
lst[3] = 'd'  # 列表的末尾元素被修改
print(lst)

f1 = shelve.open("sh_file.txt")
f1['key'] = lst
f1.close()

f2 = shelve.open("sh_file.txt", writeback=True)  # 默认参数 writeback=False
print(f2['key'])
f2['key'][3] = 'f'  # 列表的末尾元素被修改  且因参数 writeback=True 改修改可被及时写回文件
f2.close()

f3 = shelve.open("sh_file.txt")
print(f3['key'])
f2.close()