Weakref unsupported in AST

[AstraLuma]

graphql.language.ast makes extensive use of __slots__ but __weakref__ is given, breaking the weakref module.

• Python Documentation about __slots__

The use of __slots__ without __weakref__ makes it very hard to track data about AST nodes in a non-leaky way.

[AstraLuma]

My use case: My library does analysis of graphql queries, including figuring out the schema type of each node (for later directive finding).

The slots & no weakref situation means that I can't attach data directly to nodes, I'll keep the nodes around if I keep them in a dictionary, and I'll leak data if I use the object IDs.

[Cito]

Thanks for the feedback, @astronouth7303. Does it solve your problem when we add "__weakref__" to the __slots__ attribute of Node? What be the disadvantages of this change? Just a slightly higher memory consumption overall because of the additional slot, right?

[AstraLuma]

Yup, that'll fix it up nice.

I think there might be a slight memory increase, something like an extra pointer per instance. I'm not intimately familiar with what __slots__ does under the hood, though, so the above is speculation. I believe the usual rules of attributes still exist (namely that the attribute doesn't exist until it's assigned to, which in this case I'm pretty sure happens on first weakref use).