Python Day 9 (2) parameter check and multiple inheritance

One: Parameter checking (using the @property adorner to turn the method into a property call is a method)

ClassStudent(object):@property #相当于get_score函数/getterdef score (self): return self._score  @score. Setter #相当于set_score函数/setter def score (self, value): span class= "keyword" >if not isinstance (value, int): raise valueerror ( Span class= "string" > ' score must is an integer! ') if value < 0 or value >  : raise valueerror ( ' score must between 0 ~ 100! ') Self._score = value 
 To turn a getter method into a property, just add  @property  to it, and  @property  itself creates another adorner  @score. Setter , which is responsible for turning a setter method into a property assignment 
             

s = Student()>>> s.score = 60 # OK，实际转化为s.set_score(60)>>> s.score # OK，实际转化为s.get_score()60

>>> s.score = 9999Traceback (most recent call last):  ...ValueError: score must between 0 ~ 100!


You can also define read-only properties, define getter methods only, and do not define setter methods as a read-only property

 class student @property def birth (self): return self._birth  @birth. Setter def birth (self, value): Self._birth = value  @property def age return 2015-self._birth    

The above birth is a read-write property, which age is a readonly property

II: Multiple Inheritance (MixIn)

class Dog(Mammal, Runnable): pass

class Bat(Mammal, Flyable): pass

With multiple inheritance, a subclass can get all the functionality of multiple parent classes at the same time.

class Dog(Mammal, RunnableMixIn, CarnivorousMixIn): pass
MixIn的目的就是给一个类增加多个功能，这样，在设计类的时候，我们优先考虑通过多重继承来组合多个MixIn的功能，而不是设计多层次的复杂的继承关系。

Because Python allows multiple inheritance, mixin is a common design.

Only single-inherited languages, such as Java, are allowed to use the mixin design.

Python Day 9 (2) parameter check and multiple inheritance