Python升级之路( Lv6 ) 面向对象基础

class Student:
    pass  # 空语句


print(type(Student))    # <class 'type'>
print(id(Student))      # 1772468512176
Stu2 = Student
s1 = Stu2()
print(s1)   # <__main__.Student object at 0x0000019CAF6E3D90>

class 类名: 
 类变量名= 初始值

class Student:
    company = "sxd"  # 类属性


s1 = Student()
print(s1.company)

@classmethod
def 类方法名(cls [, 形参列表]):
 	方法体

class Student:
    company = 'sxd'

    @classmethod
    def printCompany(cls):
        print(cls.company)


Student.printCompany()

@staticmethod
def 静态方法名([形参列表]):
 方法体

class Student:
    company = "sxd"

    @staticmethod
    def add(a, b):
        print("{0}+{1}={2}".format(a, b, a+b))
        return a + b


Student.add(111, 222)

def 方法名(self [, 形参列表]): 
	函数体

对象.方法名([实参列表])

class Student:

    def __init__(self, name, score):
        self.name = name  # 实例属性
        self.score = score
        self.age = 18  # 增加age属性

    def say_score(self):  # 实例方法
        print(self.name, "的分数是: ", self.score)


s1 = Student("时间静止", 18)
s1.say_score()	# 调用示例方法
print(s1.age)
s1.salary = 3000  # s1对象增加salary属性
s2 = Student("不是简史", 81)
s2.say_score()
print(s2.age)

class Person:
    def make_money(self):
        print("我要挣钱啦~")

    def make_money(self, money):
        print("我要挣钱啦~今天挣到{0}元".format(money))


p1 = Person()
# p1.make_money()  # 不带参, 报: TypeError: Person.makeMoney() missing 1 required positional argument: 'money'
p1.make_money(666)

class Person:
    def work(self):
        print("努力上班！")


def play_game(self):  # 静态方法
    print("玩游戏")


def work_plus(s):
    print("上班好好工作, 下班好好玩")


Person.play = play_game
Person.work = work_plus
p = Person()
p.play()
p.work()

class Employee:
    __company = "sxd"  # 私有.通过dir查到_Employee__company

    def __init__(self, name, age):
        self.name = name
        self.__age = age

    def get_company_name(self):
        print("我的公司是: ", Employee.__company)  # 类内部可以直接访问私有属性
        print("{0}的年龄是{1}".format(self.name, self.__age))

    def __work(self):  # 私有实例方法, 通过dir可查到_Employee__work
        print("工作是人类进步的阶梯")


p1 = Employee("timePause", 18)

print(dir(Employee))
print(Employee._Employee__company)  # 在将company属性私有化后,直接调用报错, 通过dir可以查到属性_Employee__company,这种方式调用输出sxd, 从而验证规则4

# print(p1.age)   # 在age属性未私有化时, 这样可以访问
print(p1._Employee__age)  # 在age属性未私有化后, 通过这种方式可以直接访问到私有属性_Employee__age.  也验证了规则4
p1.get_company_name()

# p1.work()   # 未私有之前可以调用, 私有后调用报错: AttributeError: 'Employee' object has no attribute 'work'
p1._Employee__work()  # 私有之后. 通过这种方式可以直接访问私有熟悉_Employee__work. 也验证了规则4

class Student:
    company = "sxd"  # 类属性
    count = 0  # 类属性

    def __init__(self, name, score):
        self.name = name  # 实例属性
        self.score = score
        Student.count = Student.count + 1

    def say_score(self):  # 实例方法
        print("我的公司是: ", Student.company)
        print(self.name, "的分数是: ", self.score)


s1 = Student("时间静止", 18)    # s1是实例对象, 自动调用__init__()方法
s2 = Student("不是简史", 81)
s1.say_score()
print('一共创建{0}个Student对象'.format(Student.count))
print("s1的引用:", id(s1))
print("s2的引用:", id(s2))
print("Student的引用:", id(Student))

class Person:
    def __del__(self):
        print("销毁对象: {0}".format(self))


p1 = Person()
p2 = Person()
del p2
print("程序结束")

def f1():
    print("f1")


f1()  # 本质上也是调用了 __call__()方法


class Car:
    def __call__(self, age, money):
        print("调用__call__()方法")
        print("车龄:{0}, 金额:{1}".format(age, money))


f2 = Car()
f2(3, 289000)  # 像函数那样调用, 本质上也是调用了 __call__()

class Employee:

    def __init__(self, name, salary):
        self.name = name
        self.__salary = salary

    @property  # 相当于salary属性的getter方法
    def salary(self):
        print("月薪为{0}, 年薪为{1}".format(self.__salary, 12 * self.__salary))
        return self.__salary

    @salary.setter
    def salary(self, salary):  # 相当于salary属性的setter方法
        if 0 < salary < 1000000:
            self.__salary = salary
        else:
            print("薪水录入错误! 只能在0-1000000之间")


emp1 = Employee("时间静止", 8848.48)
print(emp1.salary)
emp1.salary = 12580
print(emp1.salary)

obj = None
obj2 = None
print(type(None))
print(id(None))
print(id(obj))
print(id(obj2))
"""输出结果
<class 'NoneType'>
140706372487160
140706372487160
140706372487160
"""

# None不是False, None不是0, None不是空字符串. None和任何其他的数据类型比较永远返回False. 
a = None
if a is None and a == None:
    print("a是None")  # 会执行
if a == False or a == 0:
    print("None不等于False")  # 不会被打印

a = []
b = ()
c = {}
d = ""
e = 0
f = None
# if语句判断时,空列表[]、空字典{}、空元组()、0等一系列代表空和无的对象会被转换成False
if (not a) and (not b) and (not c) and (not d) and (not e) and (not f):
    print("if判断时, 空列表[]、空字符串、0、None等代表空和无的对象会被转换成False")
# == 和 is 判断时, 空列表、空字符串不会自动转成 False
if a == False or d == False:
    print("==时, 空列表、空字符串不是False！")  # 不会执行
if(e == False):
    print("==时, 0会转成False")

import turtle


class MyRectangle:
    """
    设计一个名为MyRectangle的矩形类来表示矩形. 这个类包含：
    (1) 左上角顶点的坐标：x, y
    (2) 宽度和高度：width、height
    (3) 构造方法：传入x, y, width, height. 如果（x, y）不传
    则默认是0, 如果width 和height不传, 则默认是100.
    (4) 定义一个getArea() 计算面积的方法
    (5) 定义一个getPerimeter(), 计算周长的方法
    (6) 定义一个draw()方法, 使用海龟绘图绘制出这个矩形
    """
    __x = 0
    __y = 0

    def __init__(self, x, y, width, height):
        self.x = x
        self.y = y
        self.width = width
        self.height = height

    def get_area(self):
        print("该矩形面积为:", self.width * self.height)

    def get_perimeter(self):
        print("该矩形周长为:", (self.width + self.height) * 2)

    def draw(self):
        turtle.showturtle()
        turtle.write("画出该矩形, 左上角坐标为:({0},{1}), 宽为:{2}, 高为:{3}".format(self.x, self.y, self.width, self.height))
        turtle.speed(1)
        turtle.goto(self.x, self.y)
        turtle.goto(self.x, self.y - self.height)
        turtle.goto(self.x + self.width, self.y - self.height)
        turtle.goto(self.x + self.width, self.y)
        turtle.goto(self.x, self.y)


m1 = MyRectangle(0, 100, 50, 100)
m1.get_area()
m1.get_perimeter()
m1.draw()