1-2-Python基础-OOP3-多继承单继承

Python基础 OOP-03

In [7]:

# 多继承的例子
# 子类可以直接拥有父类的属性和方法，私有属性和方法除外
class Fish():
    def __init__(self,name):
        self.name = name
    def swim(self):
        print("i am swimming......")
        
class Bird():
    def __init__(self, name):
        self.name = name
        
    def fly(self):
        print("I am flying.....")

class Person():
    def __init__(self, name):
        self.name = name
        
    def work(self):
        print("Working........")
        
        

        
# 单继承的例子      
class Student(Person):
    def __init__(self, name):
        self.name = name
stu = Student("yueyue")
stu.work()
        
        
# 多继承的例子  
class SuperMan(Person, Bird, Fish):
    def __init__(self, name):
        self.name = name


class SwimMan(Person, Fish):
    def __init__(self, name):
        self.name = name
        
s = SuperMan("yueyue")
s.fly()
s.swim()

 

 

Working........
I am flying.....
i am swimming......

In [8]:

# 菱形继承问题
class A():
    pass
class B(A):
    pass
class C(A):
    pass

class D(B,C):
    pass

 

In [10]:

# 构造函数例子

class Person():
    # 对Person类进行实例化的时候
    # 姓名要确定
    # 年龄得确定
    # 地址肯定有
    def __init__(self):
        self.name = "NoNmae"
        self.age = 18
        self.address = "Studentwhonheim"
        print("In init func")

# 实例化一个人
p = Person()

 

 

In init func

In [13]:

# 构造函数的调用顺序 - 1
# 如果子类没有写构造函数，则自动向上查找，知道找到位置
class A():
    def __init__(self):
        print("A")

class B(A):
    def __init__(self):
        print("B")
        
class C(B):
    pass

# 此时，首先查找C的构造函数
# 如果没有，则向上按照MRO顺序查找父类的构造函数，知道找到为止
c = C()

 

 

B

In [14]:

# # 构造函数的调用顺序 - 2
class A():
    def __init__(self):
        print("A")

class B(A):
    def __init__(self, name):
        print("B")
        print(name)
        
class C(B):
    pass

# 此时，首先查找C的构造函数
# 如果没有，则向上按照MRO顺序查找父类的构造函数，知道找到为止
# 此时，会出现参数结构不对应错误
c = C()

 

 

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-14-4fb00a0cb98b> in <module>()
     15 # 如果没有，则向上按照MRO顺序查找父类的构造函数，知道找到为止
     16 # 此时，会出现参数结构不对应错误
---> 17 c = C()

TypeError: __init__() missing 1 required positional argument: 'name'

In [17]:

# # 构造函数的调用顺序 - 3
class A():
    def __init__(self):
        print("A")

class B(A):
    def __init__(self, name):
        print("B")
        print(name)
        
class C(B):
    # c中想扩展B的构造函数，
    # 即调用B的构造函数后在添加一些功能
    # 由两种方法实现
    
    '''
    # 第一种是通过父类名调用
    def __init__(self, name):
        # 首先调用父类构造函数
        B.__init__(self, name)
        # 其次，再增加自己的功能
        print("这是C中附加的功能")
    '''  
        
    # 第二种，使用super调用
    def __init__(self, name):
        # 首先调用父类构造函数
        super(C, self).__init__(name)
        # 其次，再增加自己的功能
        print("这是C中附加的功能")
        

# 此时，首先查找C的构造函数
# 如果没有，则向上按照MRO顺序查找父类的构造函数，知道找到为止
# 此时，会出现参数结构不对应错误
c = C("我是C")

 

 

B
我是C
这是C中附加的功能

In [22]:

# Mixin案例
class Person():
                name = "liuying"
                age = 18

                def eat(self):
                    print("EAT.......")
                    
                def drink(self):
                    print("DRINK......")
                    
                def sleep(self):
                    print("SLEEP.....")
                
class Teacher(Person):
                def work(self):
                    print("Work")

class Student(Person):
                def study(self):
                    print("Study")
                    

class Tutor(Teacher, Student):
                pass

t = Tutor()
             
print(Tutor.__mro__)
print(t.__dict__)
print(Tutor.__dict__)

print("*"*20)
class TeacherMixin():
                def work(self):
                    print("Work")

class StudentMixin():
                def study(self):
                    print("Study")
                    
class TutorM(Person, TeacherMixin, StudentMixin):
                pass

tt = TutorM()
print(TutorM.__mro__)
print(tt.__dict__)
print(TutorM.__dict__)

 

 

(<class '__main__.Tutor'>, <class '__main__.Teacher'>, <class '__main__.Student'>, <class '__main__.Person'>, <class 'object'>)
{}
{'__module__': '__main__', '__doc__': None}
********************
(<class '__main__.TutorM'>, <class '__main__.Person'>, <class '__main__.TeacherMixin'>, <class '__main__.StudentMixin'>, <class 'object'>)
{}
{'__module__': '__main__', '__doc__': None}

In [28]:

# issubclass
class A():
    pass

class B(A):
    pass

class C():
    pass

print( issubclass(B, A))
print( issubclass(C, A))
print( issubclass(B, object))

 

 

True
False
True

In [31]:

# isinstance
class A():
    pass

a = A()

print(isinstance(a, A))
print(isinstance(A, A))

 

 

True
False

In [34]:

# hasattr
class A():
    name = "NoName"
    
a = A()
print(hasattr(a, "name" ))
print(hasattr(a, "age" ))
 

 

True
False

In [36]:

# help案例
# 我想知道setattr的具体用法
help(setattr)

 

 

Help on built-in function setattr in module builtins:

setattr(obj, name, value, /)
    Sets the named attribute on the given object to the specified value.
    
    setattr(x, 'y', v) is equivalent to ``x.y = v''

In [39]:

# dir 案例
class A():
    pass

#dir(A)
a = A()
dir(a)

 

Out[39]:

['__class__',
 '__delattr__',
 '__dict__',
 '__dir__',
 '__doc__',
 '__eq__',
 '__format__',
 '__ge__',
 '__getattribute__',
 '__gt__',
 '__hash__',
 '__init__',
 '__init_subclass__',
 '__le__',
 '__lt__',
 '__module__',
 '__ne__',
 '__new__',
 '__reduce__',
 '__reduce_ex__',
 '__repr__',
 '__setattr__',
 '__sizeof__',
 '__str__',
 '__subclasshook__',
 '__weakref__']