1-2-Python基础-OOP-02-公有私有-类的实现

Python基础 OOP面向对象

02-oop.py

In [6]:

class Student():
    name = "dana"
    age = 18
    
Student.__dict__

# 实例化
yueyue = Student()
yueyue.__dict__
print(yueyue.name)

 

 

dana

In [8]:

class A():
    name = "dana"
    age = 18
    
    # 注意say的写法，参数由一个self
    def say(self):
        self.name = "aaaa"
        self.age = 200

# 此案例说明
# 类实例的属性和其对象的实例的属性在不对对象的实例属性赋值的前提下，
# 指向同一个变量
        
# 此时，A称为类实例
print(A.name)
print(A.age)

print("*" * 20)

# id可以鉴别一个变量是否和另一个变量是同一变量
print(id(A.name))
print(id(A.age))

print("*" * 20)
a = A()

print(a.name)
print(a.age)
print(id(a.name))
print(id(a.age))

 

 

dana
18
********************
140666260313176
93936169025280
********************
dana
18
140666260313176
93936169025280

In [12]:

# 此时，A称为类实例
print(A.name)
print(A.age)

print("*" * 20)

# id可以鉴别一个变量是否和另一个变量是同一变量
print(id(A.name))
print(id(A.age))

print("*" * 20)
a = A()
# 查看A内所有的属性
print(A.__dict__)
print(a.__dict__)

a.name = "yaona"
a.age = 16
print(a.__dict__)

print(a.name)
print(a.age)
print(id(a.name))
print(id(a.age))

 

 

dana
18
********************
140666260313176
93936169025280
********************
{'__module__': '__main__', 'name': 'dana', 'age': 18, 'say': <function A.say at 0x7fef6a799730>, '__dict__': <attribute '__dict__' of 'A' objects>, '__weakref__': <attribute '__weakref__' of 'A' objects>, '__doc__': None}
{}
{'name': 'yaona', 'age': 16}
yaona
16
140666251554240
93936169025216

In [15]:

class Student():
    name = "dana"
    age = 18
    
    # 注意say的写法，参数由一个self
    def say(self):
        self.name = "aaaa"
        self.age = 200
        print("My name is {0}".format(self.name))
        print("My age is {0}".format(self.age))
        
    def sayAgain(s):
      
        print("My name is {0}".format(s.name))
        print("My age is {0}".format(s.age))
          
yueyue = Student()
yueyue.say()
yueyue.sayAgain()

 

 

My name is aaaa
My age is 200
My name is aaaa
My age is 200

In [21]:

class Teacher():
    name = "dana"
    age = 19
    
    def say(self):
        self.name = "yaona"
        self.age = 17
        print("My name is {0}".format(self.name))
        # 调用类的成员变量需要用 __class__
        print("My age is {0}".format(__class__.age))
    def sayAgain():
        print(__class__.name)
        print(__class__.age )
        print("Hello, nice to see you again")
        
t = Teacher()
t.say()
# 调用绑定类函数使用类名
Teacher.sayAgain()

 

 

My name is yaona
My age is 19
dana
19
Hello, nice to see you again

In [27]:

# 关于self的案例

class A():
    name = " liuying"
    age = 18
    
    def __init__(self):
        self.name = "aaaa"
        self.age = 200
        
    def say(self):
        print(self.name)
        print(self.age)
        
class B():
    name = "bbbb"
    age = 90
    
a = A()
# 此时，系统会默认把a作为第一个参数传入函数
a.say()
   
# 此时，self被a替换
A.say(a)
# 同样可以把A作为参数传入
A.say(A)

# 此时，传入的是类实例B，因为B具有name和age属性，所以不会报错
A.say(B)

# 以上代码，利用了鸭子模型

 

 

aaaa
200
aaaa
200
 liuying
18
bbbb
90

In [36]:

# 私有变量案例

class Person():
                # name是共有的成员 
                name = "liuying"
                # __age就是私有成员
                __age = 18
                
p = Person()
# name是公有变量
print(p.name)
# __age是私有变量
print(p.__age)

 

 

liuying
19

In [37]:

# name mangling技术
print(Person.__dict__)

p._Person__age = 19
print(p._Person__age)

 

 

{'__module__': '__main__', 'name': 'liuying', '_Person__age': 18, '__dict__': <attribute '__dict__' of 'Person' objects>, '__weakref__': <attribute '__weakref__' of 'Person' objects>, '__doc__': None}
19