python中的用户定义类序列化和反序列化

Question

I am very new to python : I want to serialize and deserialize my custom object in python. Please guide me on the same. I have a sample class :

import pickle  
import json

class MyClass():   
    variable = "blah"  
    num = 10

    def function(self):
        print("this is a message inside the class.")

    def get_variable():
        return variable

    def get_num():
        return num

def main():
    myObj = MyClass()
    with open('/opt/infi/deeMyObj.txt', 'w') as output:
        pickle.dump(myObj, output,pickle.HIGHEST_PROTOCOL)

    with open('/opt/infi/deeMyObj.txt', 'r') as input:
        myObjread = pickle.load(input)
        print myObjread.get_variable()
        print myObjread.get_num()

main()

I am getting following error :

Traceback (most recent call last):

File "sample.py", line 30, in

main()

File "sample.py", line 27, in main

print myObjread.get_variable()

TypeError: get_variable() takes no arguments (1 given)

Main intention is to read the object back.

Answer 1

To expand on jasonharper's comment , your get_variable and get_num methods aren't referring to the class's member variables. They should take the object as their first argument, eg

class MyClass:
    ...
    def get_variable(self):
        return self.variable

I think your serialization code is OK, but I might be wrong.

(Aside) This is a bit off-topic, but another thing to note: when you define variables directly within the class block, they're defined on the class, not on objects of that class. That happens to work out in this case, since Python will look for a class-level variable of the same name if it can't find one on the object. However, if you store, say, a list in one of them and start modifying it, you'd end up sharing it between objects, which is probably not what you want. Instead you want to define them on in an __init__ method:

class MyClass:
    def __init__(self):
        self.variable = "blah"