练习：请把下面的Student对象的gender字段对外隐藏起来，用get_gender()和set_gender()代替，并检查参数有效性：

Discuss / Python / 练习：请把下面的Student对象的gender字段对外隐藏起来，用get_gender()和set_gender()代替，并检查参数有效性：

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#1 Created at ... [Delete] [Delete and Lock User]

class Student(object):

def __init__(self, name, gender):

self.name = name

self.__gender = gender

def get_gender(self):

return self.__gender

def set_gender(self,gender):

if gender == 'male' or 'female':

self.__gender = gender

else:

raise ValueError('Error gender')

#2 Created at ... [Delete] [Delete and Lock User]

验证失败,当输入不是 male 或者 female 无法返回错误

而是输入什么就返回什么

#3 Created at ... [Delete] [Delete and Lock User]

if gender == 'male' or 'female':

这个if判断永远为真。

#4 Created at ... [Delete] [Delete and Lock User]

的确，需要拆成两个判断才可以，为什么？

#5 Created at ... [Delete] [Delete and Lock User]

知道了，是运算符次序问题，必须将真值运算括起来否则就是先判断a == b ,然后or c，因为c永远为真，所以条件永远为真

#6 Created at ... [Delete] [Delete and Lock User]

也不对，加了括号的话则不论内容如何结构都为false，应该直接用列表和in来判断比较好

bool(a == (b or c)）这里等式右面为真值，左面为字符串，结果永远为false

而a == b or c则是左边永远为false，右面为true整个永远为true