如何在Python中完全保存/读取类

Question

som = SOM_CLASS() # includes many big difficult data structures
som.hard_work()
som.save_to_disk(filename)
#then later or another program
som = SOM_CLASS()
som.read_from_file(filename)
som.do_anythink_else()

或者

som = SOM_CLASS()
save(som)
#...
load(som)
som.work()

什么是最简单的方法来做到这一点？

Answer 1

您可以使用 pickle 进行序列化（反序列化）。它是向后兼容的，即它将在未来版本中支持所有旧协议。

import pickle

som = SOM_CLASS()
fileObject = <any file-like object>
pickle.dump(som, fileObject)
#...
som = pickle.load(fileObject)
som.work()

但请注意，如果您将 pickle 对象传输到另一台计算机，请确保连接不会被篡改，因为 pickle 可能不安全（这是每个pickle用户都应该知道的文章）。

另一种选择是旧模块 marshal。

Answer 2

我使用此代码：

import cPickle
import traceback

class someClass():
    def __init__(self):
        #set name from variable name. http://stackoverflow.com/questions/1690400/getting-an-instance-name-inside-class-init
        (filename,line_number,function_name,text)=traceback.extract_stack()[-2]
        def_name = text[:text.find('=')].strip()
        self.name = def_name

        try:
            self.load()
        except:
            ##############
            #to demonstrate
            self.someAttribute = 'bla'
            self.someAttribute2 = ['more']
            ##############

            self.save()

    def save(self):
        """save class as self.name.txt"""
        file = open(self.name+'.txt','w')
        file.write(cPickle.dumps(self.__dict__))
        file.close()

    def load(self):
        """try load self.name.txt"""
        file = open(self.name+'.txt','r')
        dataPickle = file.read()
        file.close()

        self.__dict__ = cPickle.loads(dataPickle)

此代码从其实际的类实例名称保存和加载该类。代码来自我的博客 http://www.schurpf.com/python-save-a -类/。

Answer 3

看一下 Python 的 pickle 库。

Answer 4

以这种方式使用 pickle：

import pickle
class Student:
    def __init__(self, name, age, grade):
        self.name = name
        self.age = age
        self.grade = grade # 0 - 100
    def get_grade(self):
        print (self.grade)
s1 = Student("Tim", 19, 95)

#save it
with open(f'test.pickle', 'wb') as file:
    pickle.dump(s1, file) 

#load it
with open(f'test.pickle', 'rb') as file2:
    s1_new = pickle.load(file2)

#check it
s1_new.get_grade()
# it prints 95