Question

class Student():

    NAME = ''
    DICT = {}

    def __init__(self, name):
        self.NAME = name
        self.DICT['name'] = name

    def change_DICT(self, change):
        self.DICT['name'] = change


student_one = Student('Leo')
student_two = Student('Liz')

print ('Student one NAME: ' + student_one.NAME)
print ('Student two NAME: ' + student_two.NAME)
print ('---------------------------------')
print ('Student one DICT: ' + str(student_one.DICT))
print ('Student two DICT: ' + str(student_two.DICT))
print ('---------------------------------')
student_one.change_DICT('Tom')
print ('Student one DICT: ' + str(student_one.DICT))
print ('Student two DICT: ' + str(student_two.DICT))


>> Student one NAME: Leo
>> Student two NAME: Liz
>> ---------------------------------
>> Student one DICT: {'name': 'Liz'}
>> Student two DICT: {'name': 'Liz'}
>> ---------------------------------
>> Student one DICT: {'name': 'Tom'}
>> Student two DICT: {'name': 'Tom'}

我已经玩了好几个小时但仍然无法绕过它。更改类DICT的一个实例的Student如何同步更改所有其他实例的DICT。

这是如何发生的，如果我真的需要使用dict，解决此问题的最佳方法是什么？

Answer 1

您可以通过更改DICT和NAME等类属性的初始化位置来实现所需的输出。我会举个例子。

class Student():


    def __init__(self, name):
        self.DICT = {}
        self.NAME = name
        self.DICT['name'] = name

    def change_DICT(self, change):
        self.DICT['name'] = change

student_one = Student('Leo')
student_two = Student('Liz')

print ('Student one NAME: ' + student_one.NAME)
print ('Student two NAME: ' + student_two.NAME)
print ('---------------------------------')
print ('Student one DICT: ' + str(student_one.DICT))
print ('Student two DICT: ' + str(student_two.DICT))
print ('---------------------------------')
student_one.change_DICT('Tom')
print ('Student one DICT: ' + str(student_one.DICT))
print ('Student two DICT: ' + str(student_two.DICT))

这将输出为：

Student one NAME: Leo
Student two NAME: Liz
---------------------------------
Student one DICT: {'name': 'Leo'}
Student two DICT: {'name': 'Liz'}
---------------------------------
Student one DICT: {'name': 'Tom'}
Student two DICT: {'name': 'Liz'}

在这里，您将检查字典值是否已更改。

Answer 2

您正在混合类变量和实例变量。当你在构造函数之外声明一个变量时（即__init__)以上它是一个类变量，意味着它是共享的。相反，你只需要实例变量，如下所示。

class Student():
    def __init__(self, name):
        self.NAME = name
        self.DICT = {'name': name}

    def change_DICT(self, change):
        self.DICT['name'] = change


student_one = Student('Leo')
student_two = Student('Liz')

print ('Student one NAME: ' + student_one.NAME)
print ('Student two NAME: ' + student_two.NAME)
print ('---------------------------------')
print ('Student one DICT: ' + str(student_one.DICT))
print ('Student two DICT: ' + str(student_two.DICT))
print ('---------------------------------')
student_one.change_DICT('Tom')
print ('Student one DICT: ' + str(student_one.DICT))
print ('Student two DICT: ' + str(student_two.DICT))

Python - 类实例共享类字典变量？

2 个答案: