1、打印并解释结果

class Parent(object):

x = 1

class Child1(Parent):

pass

class Child2(Parent):

pass

print(Parent.x, Child1.x, Child2.x)

Child1.x = 2

print(Parent.x, Child1.x, Child2.x)

Parent.x = 3

print(Parent.x, Child1.x, Child2.x)

1 1 1

1 2 1

3 2 3

第一行: 子类会继承父类的属性

第二行: Child1.x = 2给Child1类添加了派生属性, 属性的搜索顺序是先子类后父类

第三行: Parent.x = 3修改了父类的属性, Child2继承了Parent的x属性, Child1优先使用自身的x属性

2、打印并解释结果(多重继承的执行顺序)

class A(object):

def __init__(self):

print('A')

super(A, self).__init__()

class B(object):

def __init__(self):

print('B')

super(B, self).__init__()

class C(A):

def __init__(self):

print('C')

super(C, self).__init__()

class D(A):

def __init__(self):

print('D')

super(D, self).__init__()

class E(B, C):

def __init__(self):

print('E')

super(E, self).__init__()

class F(C, B, D):

def __init__(self):

print('F')

super(F, self).__init__()

class G(D, B):

def __init__(self):

print('G')

super(G, self).__init__()

if __name__ == '__main__':

g = G()

f = F()

G

D

A

B

F

C

B

D

A

调用类会自动触发__init__函数

新式类的多重继承按从左到右, 广度优先的顺序搜索

3、什么是新式类，什么是经典类，二者有什么区别？什么是深度优先，什么是广度优先？

新式类: 所有继承object的类及其子类都是新式类

经典类: Python2没有继承object的类及其子类都是经典类

深度优先: 当类经典类时, 多重继承时, 会按深度优先的方式查找

广度优先: 当类是新式类时, 多重继承时, 会按广度优先的方式查找

4、用面向对象的形式编写一个老师类, 老师有特征：编号、姓名、性别、年龄、等级、工资，老师类中有功能。

1.生成老师唯一编号的功能，可以用hashlib对当前时间加上老师的所有信息进行校验得到一个hash值来作为老师的编号

def create_id(self):

pass

2.获取老师所有信息

def tell_info(self):

pass

3.将老师对象序列化保存到文件里，文件名即老师的编号，提示功能如下

def save(self):

with open('老师的编号','wb') as f:

pickle.dump(self,f)

4.从文件夹中取出存储老师对象的文件，然后反序列化出老师对象,提示功能如下

def get_obj_by_id(self,id):

return pickle.load(open(id,'rb'))

5、按照定义老师的方式，再定义一个学生类

import hashlib

import time

import pickle

# 老师类

class PyTeacher:

def __init__(self, name, gender, age, level, salary):

self.name = name

self.gender = gender

self.age = age

self.level = level

self.salary = salary

self.id = self.creat_id()

def creat_id(self):

raw_id = str(time.time()) + self.name + self.gender + str(self.age) + str(self.level) + str(self.salary)

id = hashlib.md5(raw_id.encode()).hexdigest()

return id

def teach(self):

print('teaching Python...')

def tell_info(self):

print(f'ID:{teacher.id}, name:{teacher.name}, gender:{teacher.gender}, age:{teacher.age}, level:{teacher.level}, salary:{teacher.salary}')

def save(self):

with open(self.id, 'wb') as f:

pickle.dump(self, f)

print('done!')

def get_obj_by_id(self):

return pickle.load(open(self.id, 'rb'))

teacher = PyTeacher('龟叔', 'male', 18, 10, 0)

# 学生类

class PyStudent:

def __init__(self, name, gender, age, class_no, score):

self.name = name

self.gender = gender

self.age = age

self.class_no = class_no

self.score = score

self.id = self.creat_id()

def creat_id(self):

raw_id = str(time.time()) + self.name + self.gender + str(self.age) + str(self.class_no) + str(self.score)

id = hashlib.md5(raw_id.encode()).hexdigest()

return id

def learn(self):

print('learning Python...')

def tell_info(self):

print(f'''

ID:{self.id},

name:{self.name},

gender:{self.gender},

age:{self.age},

class:{self.class_no},

score:{self.score}

''')

def save(self):

with open(self.id, 'wb') as f:

pickle.dump(self, f)

print('done!')

def get_obj_by_id(self):

return pickle.load(open(self.id, 'rb'))

5、抽象老师类与学生类得到父类，用继承的方式减少代码冗余

class PyMan:

language = 'Python'

def __init__(self, name, age, gender):

self.name = name

self.age = age

self.gender = gender

def save(self):

with open(self.id, 'wb') as f:

pickle.dump(self, f)

print('done!')

def get_obj_by_id(self):

return pickle.load(open(self.id, 'rb'))

# 老师类

class PyTeacher(PyMan):

def __init__(self, name, age, gender, level, salary):

super().__init__(self, name, age, gender)

self.level = level

self.salary = salary

self.id = self.creat_id()

def creat_id(self):

raw_id = str(time.time()) + self.name + self.gender + str(self.age) + str(self.level) + str(self.salary)

id = hashlib.md5(raw_id.encode()).hexdigest()

return id

def teach(self):

print('teaching Python...')

def tell_info(self):

print(f'''

ID:{teacher.id},

name:{teacher.name},

gender:{teacher.gender},

age:{teacher.age},

level:{teacher.level},

salary:{teacher.salary}

''')

# 学生类

class PyStudent(PyMan):

def __init__(self, name, age, gender, class_no, score):

super().__init__(self, name, age, gender)

self.class_no = class_no

self.score = score

self.id = self.creat_id()

def learn(self):

print('learning Python...')

def tell_info(self):

print(f'''

ID:{self.id},

name:{self.name},

gender:{self.gender},

age:{self.age},

class:{self.class_no},

score:{self.score}

''')