python - 使用 __slots__ 有缺点吗？

Question

我正在使用 Python 3.7 和 Django。我正在阅读 __slots__ .显然，__slots__ 可用于通过提前列出所有对象属性来优化大量此类对象的内存分配。

class MyClass(object):
    __slots__ = ['name', 'identifier']
    def __init__(self, name, identifier):
        self.name = name
        self.identifier = identifier
        self.set_up()

我可能很明显的问题是为什么我们不想对所有对象都这样做？使用 __slots__ 有缺点吗？

Answer 1

Fluent Python Luciano Ramalho 列出了以下注意事项

• You must remember to redeclare __slots__ in each subclass, since the inherited attribute is ignored by the interpreter.

• Instances will only be able to have the attributes listed in __slots__, unless you include __dict__ in __slots__ — but doing so may negate the memory savings.

• Instances cannot be targets of weak references unless you remember to include __weakref__ in __slots__.