python __slot__

class Player(object):
    def __init__(self,name,age,life):
        self.name=name
        self.age=age
        self.life=life
class Player1(object):
    __slots__=("name","age","life")
    def __init__(self,name,age,life):
        self.name=name
        self.age=age
        self.life=life        

p1=Player("a",12,33)   
p1.aa="2334"  
p2=Player1("b",12,33) 
p2.bb=21323## 报错  
print(dir(p2))

print(set(dir(p1))-set(dir(p2)))