Python类的__slots__方法-优快云博客

本文链接：https://blog.youkuaiyun.com/immmt/article/details/119601238

本文探讨如何在Python中通过`__slots__`实现类属性的静态限制，以及如何在子类中扩展属性。首先介绍如何禁止类动态添加属性，然后展示如何在继承中安全地添加额外属性，并提供实例演示。

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如何给类动态添加属性：实例化后可以直接增加其他属性

class Student(object):
    def __init__(self, name, gender, score):
        self.name = name
        self.gender = gender
        self.score = score
student = Student('imaitian', 'male', 100)
# 动态增加一个属性
student.age = 18
print(student.age)
print(getattr(student, 'age'))

属性添加成功，结果：18

如何禁止添加动态属性：使用__slots__ = 限制添加属性

class Student(object):
    __slots__ = ('name', 'gender', 'score')
    def __init__(self, name, gender, score):
        self.name = name
        self.gender = gender
        self.score = score
student = Student('imaitian', 'male', 100)
# 动态增加一个属性
student.age = 18
print(student.age)
print(getattr(student, 'age'))

属性添加失败，结果为：

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

如何在继承类里添加属性：在 __slots__ = 里增加想要添加的属性

class Person(object):
    __slots__ = ('name', 'gender')
    def __init__(self, name, gender):
        self.name = name
        self.gender = gender
        
class Student(Person):
    __slots__ = ('score',)
    def __init__(self, name, gender, score):
        self.name = name
        self.gender = gender
        self.score = score
        
s = Student('imatian', 'male',100)
print(s.score)

或者：

class Person(object):
    __slots__ = ('name', 'gender')
    def __init__(self, name, gender):
        self.name = name
        self.gender = gender
        
class Student(Person):
    __slots__ = ('score',)
    def __init__(self, name, gender, score):
        super(Student, self).__init__(name, gender)
        self.score = score
        
s = Student('imatian', 'male',100)
print(s.score)