Are there disadvantages of using slots?

Question

I’m using Python 3.7 and Django. I was reading about __slots__ . Evidently, __slots__ can be used to optimize memory allocation for a large number of those objects by listing all the object properties ahead of time.

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

My perhaps obvious question is why wouldn’t we want to do this for all objects? Are there disadvantages for using __slots__?

Asked By: Dave

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Source

Answer 1

Fluent Python by Luciano Ramalho lists the following caveats

• 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__.

Answered By: Dušan Maďar

Are there disadvantages of using slots?

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Answers:

Are there disadvantages of using __slots__?

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Answers:

Are there disadvantages of using slots?