Question

我有以下代码：

class Person:
    def __init__(self,name):
        self.name = name
        self.balance = 0

    def setBalance(self, value):
        self.balance = vale

    def setName(self, name):
        self.name = name

class Main:

    def __init__(self):
        self.people = []

    def addPerson(self,name):
        self.people.append(Person(name))

    def updateBalance(self,balance,index):
        self.people[index].setBalance(50)

    print self.people[0]

main = Main()
main.addPerson("Jack")
main.updateBalance(30,0)

我编写了以下代码，以查看对象如何与数组一起工作。但是，当我尝试运行它时，出现 NameError：未定义名称'self'。我不确定自己在做什么错？

如果不清楚或需要修改，请在拒绝投票之前在评论中告知我。

非常感谢

Answer 1

您还应该传递self作为参数：

class Main:

    def __init__(self):
        self.people = []

    def addPerson(self, name):
        self.people.append(Person(name))

    def updateBalance(self, balance,index):
        self.people[index].setBalance(50)

    print people[0] #no need for self if you are calling local variable of class but this will print an empty array

您还输入了错误

class Person:
    def __init__(self,name):
        self.name = name
        self.balance = 0

    def setBalance(self, value):
        self.balance = vale --> not vale but value

    def setName(self, name):
        self.name = name

Answer 2

您的代码有几个问题：

类方法，需要引用类def ...(self, ...)
print(...)是Python3中的一个函数，必须从一个方法中调用。

以下调整使您的代码有效：

class Person:
    def __init__(self, name):
        self.name = name
        self.balance = 0

    def setBalance(self, value):
        self.balance = value

    def setName(self, name):
        self.name = name

class Main:
    def __init__(self):
        self.people = []

    def addPerson(self, name):
        self.people.append(Person(name))

    def updateBalance(self, balance, index):
        self.people[index].setBalance(50)
        print("Updating people at index %d" % index)


main = Main()
main.addPerson("Jack")
main.updateBalance(30, 0)

print (main.people[0])

打印：

Updating people at index 0
<__main__.Person instance at 0x100d065f0>

Answer 3

尽管Java或C ++等语言在其方法定义中将“ self” /“ this”自变量隐式表示为，但Python将其自定义为 explicit 。因此，您的Main类中的方法定义应如下所示：

class Main:
    def __init__(self):
        self.people = []

    def addPerson(self, name):
        self.people.append(Person(name))

    def updateBalance(self, balance, index):
        self.people[index].setBalance(50)

实际上，您以前拥有的是addPerson()方法，该方法接受了呼叫者的零自变量...并且它已重命名 {{1} }到self，这很不直观。按照约定，在Python中仅将方法的第一个参数称为“自我” ...您可以像这样轻松定义name：

addPerson()

...它完全可以正常工作。

尝试访问时未定义自我

3 个答案: