Python -- OOP高级 -- __slots__、@property

 

---

__slots__属性可以设置 允许被设置的属性

class Student:
    __slots__ = ("name", "age")

---

>>> s = Student()

>>> s.age = 25

>>> s.name = "Zoro"

>>> s.score = 100
Traceback (most recent call last):
  File "<ipython-input-38-b5a9e82f869f>", line 1, in <module>
    s.score = 100

AttributeError: 'Student' object has no attribute 'score'

当一个类中设置__slots__属性时，只有()中的属性可以动态设置

 

---

 

@property装饰器

class Student():
    @property
    def score(self):
        return self._score
        
    @score.setter
    def score(self, value):
        if not isinstance(value, int):
            raise ValueError("Score must be an integer!")
        if value < 0 or value > 100:
            raise ValueError("Score must between 0~100!")
        self._score = value

    @score.deleter
    def score(self):
        del self._score

---

>>> s = Student()
>>> s.score = 100
>>> s.score
Out[43]: 100

>>> s.score = 101
Traceback (most recent call last):
  File "<ipython-input-44-84f4bf77cd8e>", line 1, in <module>
    s.score = 101
  File "C:/Users/SQD/Desktop/@property.py", line 18, in score
    raise ValueError("Score must between 0~100!")
ValueError: Score must between 0~100!

>>> s.score = "abc"
Traceback (most recent call last):
  File "<ipython-input-45-179a51b0c6cf>", line 1, in <module>
    s.score = "abc"
  File "C:/Users/SQD/Desktop/@property.py", line 16, in score
    raise ValueError("Score must be an integer!")
ValueError: Score must be an integer!

>>> del s.score

把一个getter方法变成属性，只需要加上@property就可以了，此时，@property本身又创建了另一个装饰器@score

 

还可以设置只读属性：只有getter，没有setter

class Student:
    @property
    def birth(self):
        return self._birth
    @birth.setter
    def birth(self, value):
        self._birth = value
        
    @property
    def age(self):
        return 2015 - self._birth

---

>>> s = Student()
>>> s.birth = 1989
>>> s.age
Out[57]: 26

>>> s.age = 27
Traceback (most recent call last):
  File "<ipython-input-58-03895bf010a3>", line 1, in <module>
    s.age = 27

AttributeError: can't set attribute