作业20

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'))