新对象正被前一个对象覆盖

Question

我目前正在尝试简单的python类示例。我有一个父类（人）和一个子类（联系人）。

我用两个不同的对象c1和c2实例化子类。 C2正在取代C1。我究竟做错了什么 ？

#!/bin/python3 

import time 
from time import sleep 

class Person (object): 
    id = 0 
    name = None 
    fields = {} 

    def __init__(self): 
     ctime = time.strftime("%Y-%m-%d %H:%M:%S") 
     self.fields.update({"create_time":ctime, 
          "write_time" :ctime}) 
     Person.id+=1 

    def check_keys (self,vals): 
     for k in vals: 
      if not k in self.fields.keys(): 
       raise Exception("Key %s doesnot exists"%k) 

    def update(self,*args,**kwargs): 
     vals = kwargs['vals'] 
     self.check_keys(vals) 
     self.fields.update(vals) 
     ctime = time.strftime("%Y-%m-%d %H:%M:%S") 
     self.fields.update({"write_time":ctime}) 

    def write(self,*args,**kwargs): 
     vals = kwargs['vals'] 
     self.check_keys(vals) 
     self.fields.update(vals) 

    def detail (self): 
     print ("Model Name is ",self.name) 
     for k,v in self.fields.items(): 
      print("key:",k," value:",v) 
     print ("#"*50) 

    def get_id(self): 
     return self.id 

class Contact (Person): 
    name="contact" 
    contact_id = 0 
    fields = { 
     'id':None, 
     'name':None, 
     'age':None, 
    } 

c1 = Contact() 
c1.update(vals={'name':'sijan','age':31,'id':c1.get_id()}) 
sleep(1) 
c1.update(vals={'name':'sijan Shs'}) 

print ("calling contact 2") 

c2 = Contact() 
c2.update(vals={'name':'Aurelia','age':32,'id':c2.get_id()}) 

print ("calling contact 1") 
c1.detail() 
print ("calling contact 1") 
c2.detail() 

下面是从过去的2 c1.detail输出样本（）和c2.detail（）

calling contact 1 
Model Name is contact 
key: id value: 2 
key: name value: Aurelia 
key: age value: 32 
key: create_time value: 2017-03-19 15:35:54 
key: write_time value: 2017-03-19 15:35:54 
################################################## 
calling contact 2 
Model Name is contact 
key: id value: 2 
key: name value: Aurelia 
key: age value: 32 
key: create_time value: 2017-03-19 15:35:54 
key: write_time value: 2017-03-19 15:35:54 
################################################# 

我相信它应该是：

calling contact 1 
Model Name is contact 
key: id value: 1 
key: name value: Sijan Shs 
key: age value: 31 
key: create_time value: 2017-03-19 15:35:53 
key: write_time value: 2017-03-19 15:35:54 
################################################## 
calling contact 2 
Model Name is contact 
key: id value: 2 
key: name value: Aurelia 
key: age value: 32 
key: create_time value: 2017-03-19 15:35:54 
key: write_time value: 2017-03-19 15:35:54 
################################################# 

我纺我的脑袋想要弄清楚发生了什么事。如果我使用父类，它可以平滑运行（即预测的行为，即不同的数据）。但是我很难理解为什么这个子类会这样做？我错过了一些东西？

UPDATE

什么，我想实现的是：

我将有几类和每个班级都会有自己独特的领域，即forexample地址地址名称。我怎样才能实现这一点，而不添加字段字典给父母？ 例

class Address(Person): 
    fields={ 
     'address':None 
    } 

非常感谢球员， 这是工作，

#!/bin/python3 

import time 
from time import sleep 

class Person (object): 
    id = 0 
    name = None 
    fields = {} 

    def __init__(self): 
     ctime = time.strftime("%Y-%m-%d %H:%M:%S") 
     self.fields.update({"create_time":ctime, 
          "write_time" :ctime}) 
     Person.id+=1 

    def check_keys (self,vals): 
     for k in vals: 
      if not k in self.fields.keys(): 
       raise Exception("Key %s doesnot exists"%k) 

    def update(self,*args,**kwargs): 
     vals = kwargs['vals'] 
     self.check_keys(vals) 
     self.fields.update(vals) 
     ctime = time.strftime("%Y-%m-%d %H:%M:%S") 
     self.fields.update({"write_time":ctime}) 

    def write(self,*args,**kwargs): 
     vals = kwargs['vals'] 
     self.check_keys(vals) 
     self.fields.update(vals) 

    def detail (self): 
     print ("Model Name is ",self.name) 
     for k,v in self.fields.items(): 
      print("key:",k," value:",v) 
     print ("#"*50) 

    def get_id(self): 
     return self.id 

class Contact (Person): 


    def __init__(self): 
     self.name="contact" 
     self.fields = { 
      'id':None, 
      'name':None, 
      'age':None 
     } 
     super(Contact,self).__init__() 


ca = Contact() 
ca.update(vals={'name':'sijan','age':31,'id':ca.get_id()}) 
sleep(1) 
ca.update(vals={'name':'sijan Shs'}) 
ca.detail() 

cb = Contact() 
cb.detail() 
cb.update(vals={'name':'Aurelia','age':32,'id':cb.get_id()}) 

print ("calling contact 1") 
ca.detail() 
print ("calling contact 2") 
cb.detail() 

Answer 1

name，id，fields是类成员，因此在创建从Person继承的Contact的实例时，不会实例化新值。

你想要做的是为联系人的每个新实例创建一组新的属性名称，ID，字段。

下面的代码会这样做。注意它是如何定义的ID，名称，域是添加当它草签的情况下（在__init__功能）

因为每个人都有姓名，身份证，我没有领域有启动他们 的联系类也是如此。请参阅Contact类的定义，以获得继承的更清晰的实现。

#!/bin/python3 

import time 
from time import sleep 

class Person (object): 
    # id = 0 
    # name = None 
    # fields = {} 

    def __init__(self): 
     self.id = 0 
     self.name = None 
     self.fields = { 
      'id':None, 
      'name':None, 
      'age':None, 
     } 

     ctime = time.strftime("%Y-%m-%d %H:%M:%S") 
     self.fields.update({"create_time":ctime, 
          "write_time" :ctime}) 
     self.id+=1 

    def check_keys (self,vals): 
     for k in vals: 
      if not k in self.fields.keys(): 
       raise Exception("Key %s doesnot exists"%k) 

    def update(self,*args,**kwargs): 
     vals = kwargs['vals'] 
     self.check_keys(vals) 
     self.fields.update(vals) 
     ctime = time.strftime("%Y-%m-%d %H:%M:%S") 
     self.fields.update({"write_time":ctime}) 

    def write(self,*args,**kwargs): 
     vals = kwargs['vals'] 
     self.check_keys(vals) 
     self.fields.update(vals) 

    def detail (self): 
     print ("Model Name is ",self.name) 
     for k,v in self.fields.items(): 
      print("key:",k," value:",v) 
     print ("#"*50) 

    def get_id(self): 
     return self.id 

class Contact (Person): 
    def __init__(self): 
     super(Contact, self).__init__() 
     self.contact_id = 0 


c1 = Contact() 
c1.update(vals={'name':'sijan','age':31,'id':c1.get_id()}) 
# sleep(1) 
c1.update(vals={'name':'sijan Shs'}) 

print ("calling contact 2") 

c2 = Contact() 
c2.update(vals={'name':'Aurelia','age':32,'id':c2.get_id()}) 

print ("calling contact 1") 
c1.detail() 
print ("calling contact 1") 
c2.detail() 

Answer 2

这是因为你引用类变量，而不是实例变量。从docs：

一般来说，实例变量是唯一的每个实例和类变量数据是由类的所有实例共享的属性和方法：

class Dog: 
    kind = 'canine'   # class variable shared by all instances 

    def __init__(self, name): 
     self.name = name # instance variable unique to each instance 

相反，可以写你的类如下：

class Person(object): 
     self.id = 0 
     self.name = None 
     self.fields = {} 

# rest of the class ... 

class Contact (Person): 
    self.name="contact" 
    self.contact_id = 0 
    self.fields = { 
     'id':None, 
     'name':None, 
     'age':None, 
    } 

# rest of the class ...