Question

我需要一些帮助来理解类的python作用域。

例如，这是一个非常有效的程序，这对我来说很有意义

import json

class Person(object):
    def __init__(self, firstname, lastname, age,address):
        self.firstname = firstname
        self.age = age
        self.lastname = lastname
        self.address = address
class Address(object):
    def __init__(self,zipcode,state):
        self.zipcode = zipcode
        self.state = state



personlist = []
for count in range(5):
    address = Address("41111","statename")
    person = Person("test","test",21,address)
    print(count)
    personlist.append(person)
jsonlist = []
for Person in personlist:
    print Person.firstname
    d = {}
    d['firstname'] = Person.firstname
    d['lastname'] = Person.lastname
    d['age'] = Person.age
    d['zipcode'] = Person.address.zipcode
    d['state'] = Person.address.state
    jsonlist.append(d)
jsondict = {}
jsondict["People"] = jsonlist
jsondict["success"] = 1

json_data = json.dumps(jsondict, indent =4)

print json_data

但是这个下一个程序给了我一个错误

import json

class Person(object):
    def __init__(self, firstname, lastname, age,address):
        self.firstname = firstname
        self.age = age
        self.lastname = lastname
        self.address = address
class Address(object):
    def __init__(self,zipcode,state):
        self.zipcode = zipcode
        self.state = state


def main():
    personlist = []
    for count in range(5):
        address = Address("41111","statename")
        person = Person("test","test",21,address)
        print(count)
        personlist.append(person)
    jsonlist = []
    for Person in personlist:
        print Person.firstname
        d = {}
        d['firstname'] = Person.firstname
        d['lastname'] = Person.lastname
        d['age'] = Person.age
        d['zipcode'] = Person.address.zipcode
        d['state'] = Person.address.state
        jsonlist.append(d)
    jsondict = {}
    jsondict["People"] = jsonlist
    jsondict["success"] = 1

    json_data = json.dumps(jsondict, indent =4)

    print json_data
main()

我的问题是为什么在空白区域中创建类有效但在函数内创建它们无效。有没有办法在main函数中创建它们并且它有效？

编辑：

错误是文件＆＃34; jsontest.py＆＃34;，第9行，主要 person = Person（＆＃34; test＆＃34;，＆＃34; test＆＃34;，21，address） UnboundLocalError：局部变量＆＃39; Person＆＃39;在分配前引用

Answer 1

问题是您使用的变量与您的班级Person同名（也称为＃34;阴影＆＃34;）：

for Person in personlist:

Python检测到您将其用作局部变量并引发错误：

UnboundLocalError：局部变量＆＃39; Person＆＃39;以前引用过分配

表示您尝试在以下行中分配之前使用局部变量：

person = Person("test","test",21,address)

您可以找到有关它的更多信息here

Python对象范围问题

1 个答案: