本部分练习Python高级面向对象内容，主要学习__slots__和@property相关用法，详见代码：
# 1. 使用__slots__，限制允许动态绑定到实例上的属性或方法
from types import MethodType
class Student():
# 使用__slot__ 限制绑定属性，只允许绑定如下属性或者方法。
__slots__ = ("age", "set_age")
pass
# 给实例绑定属性，对其他实例无效
stu1 = Student()
stu1.age = 18
print(stu1.age)
stu2 = Student()
# print(stu2.age)，会报错，
# 类绑定属性，所有实例都有
Student.type = "Pupil"
print(stu2.type)
def set_age(self, age):
self.age = age
# 给实例绑定方法
stu2.set_age = MethodType(set_age, stu2)
stu2.set_age(25)
print(stu2.age)
# 测试子类__slots__
class GraduateStudent(Student):
__slots__ = ("name")
g_stu1 = GraduateStudent()
g_stu1.name = "G_Stu_name"
print(g_stu1.name)
# stu1.name = "Name" 会报错
# 可允许绑定范围为子类和父类并集，若父类无限制，实际等于子类可以任意绑定
g_stu1.age = 11
print(g_stu1.age)
# 2. 使用@property，加在方法上，使get set方法变成属性。使类似stu1.score这样直接的属性赋值走方法，实现封装和校验等需求
class StudentPro():
@property
def score(self):
return self.__score
@score.setter
def score(self, value):
if value > 100:
print("Invalid score value.", value, "Score must be between 0 and 100.")
self.__score = value
stu_pro_one = StudentPro()
stu_pro_one.score = 99
print(stu_pro_one.score)
stu_pro_one.score = 101
# 练习 请利用@property给一个Screen对象加上width和height属性，以及一个只读属性resolution
class Screen(object):
@property
def width(self):
return self.__width
@width.setter
def width(self, value):
self.__width = value
@property
def height(self):
return self.__height
@height.setter
def height(self, value):
self.__height = value
@property
def resolution(self):
return self.__width * self.__height
# 测试:
s = Screen()
s.width = 1024
s.height = 768
print('resolution =', s.resolution)
if s.resolution == 786432:
print('测试通过!')
else:
print('测试失败!')
