day-20 作业

day 20 作业

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)
Child1.x = 2
print(Parent.x, Child1.x, Child2.x)
Parent.x = 3
print(Parent.x, Child1.x, Child2.x)

运行结果：

1 1 1 
1 2 1 
3 2 3

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()

运行结果：

G
D
A
B
F
C
B
D
A

Process finished with exit code 0

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：继承 object 的类以及该类的子类，python3 中所有的类都是新式类
- 经典类：没有继承 object 的类以及该类的子类，只有 python2 中才有经典类
区别：有没有继承 object
- 深度优先：按照继承顺序向上查找，一直找到最顶层的类
- 广度优先：按照继承顺序向上查找，最后查找 object

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。

import hashlib
import datetime
import pickle

class Teacher:
    def __init__(self, name, sex, age, level, salary, teacher_id=None):
        self.id = id
        self.name = name
        self.sex = sex
        self.age = age
        self.level = level
        self.salary = salary

    def func(self):
        pass

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 creat_id(self):
	msg = f'{datetime.datetime.now()}+{self.name}+{self.sex}+{self.age}'
	self.teacher_id = hashlib.md5(msg.encode('utf-8')).hexdigest()

	return self.teacher_id

获取老师所有信息

def tell_info(self):
    for k, v in self.__dict__.items():
        print(k.ljust(10), v)

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(f'{self.id}', 'wb') as fw:
        data = self.__dict__
        pickle.dump(data, fw)

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):
	with open(f'{self.id}', 'rb')as fr:
		data = pickle.load(fr)
		for k, v in data.items():
			print(k.ljust(10), v)

按照定义老师的方式，再定义一个学生类

class Student:
    def __init__(self, name, sex, age, course=None, student_id=None):
        self.name = name
        self.student_id = student_id
        self.sex = sex
        self.age = age
        self.course = course

    def creat_id(self):
        msg = f'{datetime.datetime.now()}+{self.name}+{self.sex}+{self.age}'
        self.student_id = hashlib.md5(msg.encode('utf-8')).hexdigest()

        return self.student_id

    def choose_course(self, *args):
        self.course = args
        return self.course

    def tell_info(self):
        for k, v in self.__dict__.items():
            print(k.ljust(15), v)

    def save(self):
        with open(f'{self.student_id}.pkl', 'wb') as fw:
            data = self.__dict__
            pickle.dump(data, fw)

    def get_obj_by_id(self):
        with open(f'{self.student_id}.pkl', 'rb')as fr:
            data = pickle.load(fr)
            for k, v in data.items():
                print(k.ljust(15), v)

分别实例化一个老师、一个学生对象：

# 实例化老师对象
teacher1 = Teacher('tom', 'male', 26, 5, 3000)
teacher1_id = teacher1.creat_id()
teacher1.tell_info()
teacher1.save()
teacher1.get_obj_by_id()

# 实例化学生对象
student1 = Student('jack', 'male', 18)
student1_id = student1.creat_id()
student1_course = student1.choose_course('python','linux')
student1.tell_info()
student1.save()
student1.get_obj_by_id()

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 pickle
import datetime

class People(object):
    def __init__(self, name, sex, age, ):
        self.name = name
        self.sex = sex
        self.age = age

    def tell_info(self):
        for k, v in self.__dict__.items():
            print(k.ljust(15), v)


class Teacher(People):
    def __init__(self, name, sex, age, level, salary, teacher_id=None):
        super().__init__(name, sex, age)
        self.level = level
        self.salary = salary
        self.teacher_id = teacher_id

    def creat_id(self):
        msg = f'{datetime.datetime.now()}+{self.name}+{self.sex}+{self.age}'
        self.teacher_id = hashlib.md5(msg.encode('utf-8')).hexdigest()

        return self.teacher_id

    def save(self):
        with open(f'{self.teacher_id}.pkl', 'wb') as fw:
            data = self.__dict__
            pickle.dump(data, fw)

    def get_obj_by_id(self):
        with open(f'{self.teacher_id}.pkl', 'rb')as fr:
            data = pickle.load(fr)
            for k, v in data.items():
                print(k.ljust(15), v)


class Student(People):
    def __init__(self, name, sex, age, student_id=None, course=None):
        super().__init__(name, sex, age)
        self.student_id = student_id
        self.course = course

    def creat_id(self):
        msg = f'{datetime.datetime.now()}+{self.name}+{self.sex}+{self.age}'
        self.student_id = hashlib.md5(msg.encode('utf-8')).hexdigest()

        return self.student_id

    def save(self):
        with open(f'{self.student_id}.pkl', 'wb') as fw:
            data = self.__dict__
            pickle.dump(data, fw)

    def get_obj_by_id(self):
        with open(f'{self.student_id}.pkl', 'rb')as fr:
            data = pickle.load(fr)
            for k, v in data.items():
                print(k.ljust(15), v)

    def choose_course(self, *args):
        self.course = args
        return self.course


teacher2 = Teacher('alex', 'male', 30, 5, 40000)

teacher2_id = teacher2.creat_id()

teacher2.tell_info()

teacher2.save()
teacher2.get_obj_by_id()

print('*' * 30)

student2 = Student('Jane', 'femal', 18)
student2_id = student2.creat_id()
student2_course = student2.choose_course('linux', 'python')
student2.tell_info()
student2.save()
student2.get_obj_by_id()

posted @ 2019-10-10 19:56 Yugaliii 阅读(78) 评论(0) 编辑收藏举报

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day-20 作业

day 20 作业

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