Question

我正在将类提交扩展到SmsSubmission。但是，当我执行print x.sender时，构造函数不会被初始化。我期待test sender，但输出为None。

这里有什么问题？

class Submission():
    sender = None

    def __init__(self):
        self.sender = 'test sender'

class SmsSubmission(Submission):
    message = None

    def __init__(self):
        self.message = 'test message'


x = SmsSubmission()

print x.sender

DEMO

Answer 1

您没有在子类中调用构造函数。您需要使用Submission.__init__()或使用super()明确调用它。

另请注意，当您使用Python 2时，您的基类应该继承自object，以确保它是新式的类。

class Submission(object):
    sender = None

    def __init__(self):
        self.sender = 'test sender'

class SmsSubmission(Submission):
    message = None

    def __init__(self):
        Submission.__init__(self) # Calls the Submission constructor
        # super(SmsSubmission, self).__init__() 
        self.message = 'test message'


x = SmsSubmission()

print x.sender

扩展类没有运行构造函数

1 个答案: