今日作业
1、下面这段代码的输出结果将是什么？请解释。
class Parent(object):
x = 1
class Child1(Parent):
pass
class Child2(Parent):
pass
print(Parent.x, Child1.x, Child2.x)
#Parent.x = 1 Child1.x = 1 Child2.x = 1
Child1.x = 2
print(Parent.x, Child1.x, Child2.x)
#Parent.x = 1 Child1.x = 2 Child2.x = 1
Parent.x = 3
print(Parent.x, Child1.x, Child2.x)
#Parent.x = 3 Child1.x = 2 Child2.x = 3
#解释：子类先从自己的属性中中查找属性，如果找不到就去父类中查找
2、多重继承的执行顺序，请解答以下输出结果是什么？并解释。
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新式类的查找从左边一条支路开始查找，找到两条分支共同的父类前面那个类，然后返回查找下一条分支，直到找完所有的分支，然后再找共同的父类。
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？
直接或者间接继承object类的都是新式类，没有继承object类的都是经典类，区别就是有没有继承object类。
深度优先是经典类查找属性的方式，即从左向右一个分支一个分支找，而且如果分支有公共父类，在第一条分支中就会把这个父类查找了。
广度优先是新式类查找属性的方式，它和深度优先的区别就是最后查找公共父类。
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'))
import hashlib
import datetime,json,os
class Teachers:
def __init__(self,name,gender,age,level,sal):
self.name = name
self.gender = gender
self.age = age
self.level = level
self.sal = sal
def number(self):
num = hashlib.md5()
tim = datetime.date.today()
lt = [self.name,self.gender,self.level,self.sal,str(tim)]
code = ','.join(lt)
num.update(code.encode('utf-8'))
return num.hexdigest()
def tell_info(self):
dic = {'name':self.name, 'gender':self.gender,'level': self.level, 'sal':self.sal, 'number':self.number()}
return dic
def save(self):
path = os.path.join(os.path.dirname(__file__),f'{self.number()}.json')
with open(path, 'w',encoding='utf8') as f:
json.dump(self.tell_info(), f)
def get_obj_by_id(self, id):
path = os.path.join(os.path.dirname(__file__), f'{self.number()}.json')
return json.load(open(path, 'r',encoding='utf8'))
tech1 = Teachers('lihua','男','18','10','3w')
print(tech1.number())
print(tech1.tell_info())
print(tech1.get_obj_by_id('cd2cb2879f80402d884cd7436b4d678f'))
tech1.save()
5、按照定义老师的方式，再定义一个学生类
import hashlib
import datetime,json,os
class Students:
def __init__(self,name,gender,age):
self.name = name
self.gender = gender
self.age = age
def number(self):
num = hashlib.md5()
tim = datetime.date.today()
lt = [self.name,self.gender,str(tim)]
code = ','.join(lt)
num.update(code.encode('utf-8'))
return num.hexdigest()
def tell_info(self):
dic = {'name':self.name, 'gender':self.gender, 'number':self.number()}
return dic
def save(self):
path = os.path.join(os.path.dirname(__file__),f'{self.number()}.json')
with open(path, 'w',encoding='utf8') as f:
json.dump(self.tell_info(), f)
def get_obj_by_id(self, id):
path = os.path.join(os.path.dirname(__file__), f'{self.number()}.json')
return json.load(open(path, 'r',encoding='utf8'))
stu1 = Students('lihua','男','18')
print(stu1.number())
print(stu1.tell_info())
print(stu1.get_obj_by_id('13fc699c802549e3080d9c788355cefe'))
stu1.save()
6、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
import hashlib
import datetime,json,os
class School:
def __init__(self,name,gender,age):
self.name = name
self.gender = gender
self.age = age
def number(self):
num = hashlib.md5()
tim = datetime.date.today()
lt = [self.name,self.gender,str(tim)]
code = ','.join(lt)
num.update(code.encode('utf-8'))
return num.hexdigest()
def tell_info(self):
dic = {'name':self.name, 'gender':self.gender, 'number':self.number()}
return dic
def save(self):
path = os.path.join(os.path.dirname(__file__),f'{self.number()}.json')
with open(path, 'w',encoding='utf8') as f:
json.dump(self.tell_info(), f)
def get_obj_by_id(self, id):
path = os.path.join(os.path.dirname(__file__), f'{self.number()}.json')
return json.load(open(path, 'r',encoding='utf8'))
class Teachers(School):
def __init__(self,name,gender,age,level,sal):
super().__init__(name,gender,age)
self.level = level
self.sal = sal
def tell_info(self):
dic = {'name':self.name, 'gender':self.gender,'level': self.level, 'sal':self.sal, 'number':self.number()}
return dic
class Students(School):
def __init__(self, name, gender, age, skill):
super().__init__(name, gender, age)
self.skill = skill
def tell_info(self):
dic = {'name':self.name, 'gender':self.gender, 'skill':self.skill, 'number':self.number()}
return dic
stu1 = Students('lihua','男','18','learn')
print(stu1.number())
print(stu1.tell_info())
print(stu1.get_obj_by_id('13fc699c802549e3080d9c788355cefe'))
stu1.save()
tech1 = Teachers('zhanghua','男','18','10','3w')
tech1.save()
print(tech1.number())
print(tech1.tell_info())
print(tech1.get_obj_by_id('cd2cb2879f80402d884cd7436b4d678f'))