Implement gc methods (traverse, clear) for immutable objects

[MatthieuDartiailh]

Hi,

I have a use case where a frozen object need to store a reference to a Python objects (Option<HashMap<String, Py>>). Because I store a Python object, I believe I should implement the equivalent of tp_traverse and tp_clear. However since the object is frozen I cannot get a mutable reference and hence implement clear.

Is this a case where one can skip those implementation and if not how can I implement clear ?

[davidhewitt]

You can skip tp_clear on immutable objects. (Presumably to create a cycle, some other part of the chain must be mutable, and that part should implement tp_clear.)

[MatthieuDartiailh]

Thanks for your answer @davidhewitt. Indeed it makes sense.

It may be worth pointing it explicitly in the documentation. Maybe as part of #5663