创建大量实例节省内存 slots

# 使用__slots__要注意，__slots__定义的属性仅对当前类实例起作用，对继承的子类是不起作用的

import sys


class Player(object):
    def __init__(self, uid, name, status=0, level=1):
        self.uid = uid
        self.name = name
        self.status = status
        self.level = level


class Player2(object):
    # 为节省内存，阻止动态绑定属性，减少实例中的__dict__，从而达到减少内存开销的目的
    __slots__ = ['uid', 'name', 'status', 'level']

    def __init__(self, uid, name, status=0, level=1):
        self.uid = uid
        self.name = name
        self.status = status
        self.level = level


p1 = Player('0001', 'Jim')
p2 = Player2('0001', 'Jim')

print(dir(p1))
print(dir(p2))
print('*'*80)
print(set(dir(p1)) - set(dir(p2)))  # {'__dict__', '__weakref__'}

# 动态绑定属性
print(p1.__dict__)  # 动态绑定属性 {'level': 1, 'status': 0, 'uid': '0001', 'name': 'Jim'}

# 添加属性
p1.x = 123
print(p1.__dict__)  # {'name': 'Jim', 'uid': '0001', 'x': 123, 'level': 1, 'status': 0}
p1.__dict__['y'] = 99
print(p1.y)  # 99

# 删除属性
delattr(p1, 'x')  # 删除p1的x属性
print(p1.__dict__)  # {'level': 1, 'y': 99, 'uid': '0001', 'status': 0, 'name': 'Jim'}
print('*'*80)
print(sys.getsizeof(p1.__dict__))  # 164