python3 (twenty-four) subClas

"" " Inherited polymorphism " "" 
__author__ = ' shaozhiqi ' 


# ----------------- --------------- parent --------- 
class Animal (Object):
     DEF RUN (Self):
         Print ( ' Animal IS running ... ' ) 


# ----------------- subclass ------------------------ 
class Dog (Animal):
     Pass 


# ---------------- - subclass ---------------------------------------- 
class Cat (Animal):
     Pass 


# ------------------- subclass instance -------------------------- ----------- 
Dog = Dog () 
dog.run ()   # Animal is running...

cat = Cat()
cat.run()  # Animal is running...


# --------------------重新定义dog 有自己的run方法-------------------
class Dog(Animal):

    def run(self):
        print('Dog is running...')

    def eat(self):
        print('Dog eating meat...')


dog = Dog()
dog.run()  # Dog is running...
dog.eat()  # Dog eating meat...
#When the parent class and subclass there the same run () method, we say, sub-class run () covering the run parent class (), when the code is running, always calls the run subclass () . 
# In this way, we get another benefit of inheritance: polymorphism. 
# Subclass, the type of data that it can also be seen as a parent. However, in turn, will not do: 
Print (isinstance (Dog, Dog))   # True 
Print (isinstance (Dog, Animal))   # True 
A = Animal ()
 Print (isinstance (A, Dog))   # False 


# ---- -------------------------adaptation----------------------- ----------- 
DEF run_selfrun (Animal): 
    animal.run () 


run_selfrun (A)   # Animal IS running ... 
run_selfrun (Dog)   # Dog IS running ... 
#Animal a new subclass, run_selfrun () does not require any modification, this method can extract business upward, 
# fact, any dependency or as a function of Animal method parameters are used without modification to normal operation the reason is that polymorphic. 

# Closing principle: 
# extended open: Animal allow new subclasses; 
# closed for modification: Animal no modification dependent type run_selfrun () function and the like.