python3中使用__slots__限定实例属性操作分析

# 类定义
class Person(object):
  pass

p = Person()
p.name = "jadeshu"
print(p.name)

# 类定义
class Person(object):
  pass
p = Person()
p.name = "jadeshu"
print(p.name)
def set_age(self, age): # 定义一个函数作为实例方法
  self.age = age
from types import MethodType
p.set_age = MethodType(set_age, p)
p.set_age(25)
print(p.age)

p2 = Person() #创建新的实例
p2.set_age(25) #调用方法

def set_score(self, score):
  self.score = score
Person.set_score = set_score
p.set_score(80)
print(p.score)

p.set_score(80)
p2 = Person()
p2.set_score(100)
print(p.score)
print(p2.score)

class Person(object):
  __slots__ = ('name', 'age') # 用tuple定义允许绑定的属性名称

>>> s = Person() # 创建新的实例
>>> s.name = 'jadeshu' # 绑定属性'name'
>>> s.age = 25 # 绑定属性'age'
>>> s.score = 99 # 绑定属性'score'
Traceback (most recent call last):
 File "<stdin>", line 1, in <module>
AttributeError: 'Student' object has no attribute 'score'

>>> class Student(Person):
...   pass
...
>>> s = Student()
>>> s.score = 9999