如何將類對象浸入文本文件並讀取它？

Question

if __name__ == "__main__": 
    h1 = Person(5) 
    print (h1) 

如上所示，我需要將類Person的對象h1另存爲文本文件（.txt）。我想知道如何實現這種持久性並將其讀回來？

一些用戶建議使用泡菜，我想我可能需要更多的細節在這裏。

Answer 1

這是一個可能的解決方案，讓你開始。我改名的人實例名稱和更改參數的名稱;-)

#! /usr/bin/env python 
"""Note: Documentation clearly states, that classes can be pickled, 
but only iff they "are defined at the top level of a module".""" 
from __future__ import print_function 

import pickle 


class Person(object): 
    """Minimal class to showcase (un)pickle.""" 
    FULL_NAME_DEFAULT = 'N.N.' 

    def __init__(self, full_name=None): 
     """Detected initializer (show unpickling behaviour).""" 
     if full_name is not None: 
      self.full_name = full_name 
     else: 
      self.full_name = self.FULL_NAME_DEFAULT 
     print("Initializer called!") 
     self.say_hello() 

    def say_hello(self): 
     """A method to say a personalized hello.""" 
     print("Hello! My name is '%s'" % (self.full_name,)) 


def main(): 
    """Drive the dumps and loads of Person instances.""" 
    number_one = Person("Jane Awsome") 
    print(number_one) 
    print("# Serialize the person number_one ... with default protocol:") 
    serialized_person = pickle.dumps(number_one) 
    print("# Dump of the data representing the serialized_person:") 
    print(serialized_person) 
    print("# Now for something completely different ...") 
    reborn = pickle.loads(serialized_person) 
    print("# Back again a copy of number_one, no __init__ called ;-)") 
    reborn.say_hello() 

if __name__ == "__main__": 
    main() 

被我的機器上，並與Python運行時V2這導致：

Initializer called! 
Hello! My name is 'Jane Awsome' 
<__main__.Person object at 0x102e730d0> 
# Serialize the person number_one ... with default protocol: 
# Dump of the data representing the serialized_person: 
ccopy_reg 
_reconstructor 
p0 
(c__main__ 
Person 
p1 
c__builtin__ 
object 
p2 
Ntp3 
Rp4 
(dp5 
S'full_name' 
p6 
S'Jane Awsome' 
p7 
sb. 
# Now for something completely different ... 
# Back again a copy of number_one, no __init__ called ;-) 
Hello! My name is 'Jane Awsome' 

與Python V3伏法：

Initializer called! 
Hello! My name is 'Jane Awsome' 
<__main__.Person object at 0x1010c8780> 
# Serialize the person number_one ... with default protocol: 
# Dump of the data representing the serialized_person: 
b'\x80\x03c__main__\nPerson\nq\x00)\x81q\x01}q\x02X\t\x00\x00\x00full_nameq\x03X\x0b\x00\x00\x00Jane Awsomeq\x04sb.' 
# Now for something completely different ... 
# Back again a copy of number_one, no __init__ called ;-) 
Hello! My name is 'Jane Awsome' 

默認的協議改變了我的猜測:-)

請儘量擡頭看您可能需要的詳細信息用於擴展和適用您的使用案例，例如，在規範性文檔中。 12.1. pickle — Python object serialization

...如果數據可能已經過調節，那麼在取消打印時務必小心，因爲您必須依賴您對此通道的信任。這是一個強大的。

所以就像使用JSON和其他（de）序列化模塊一樣，還有針對字符串，文件等進行優化的方法。您可以輕鬆地在文檔中閱讀它。這裏我使用了dumps（）和loads（），後綴s代表字符串。

對於序列化人員（這裏是一個字符串變量）的內容輸出到一個文件，在xou中回讀可以很容易地在前述優秀的Python文檔中查看。