Feature or enhancement

Proposal:

Immortal objects might lead to some unexpected results for users that are (unfortunately) messing with reference count details, as seen in#127191; but currently, there's no way to determine what objects are actually immortal.

Immortality is an implementation detail, but it still does affect reference counting, and given that it's not very safe to rely on very specific reference counts, we don't want the only way to check for immortality to be viasys.getrefcount. So, given that we already havesys._is_interned, it seems fitting to add asys._is_immortal alongside it.

If we go with this, I think it's also a good idea to note it in some of the documentation. For example,sys.getrefcount says this:

some objects areimmortal and have a very high refcount that does not reflect the actual number of references.

Here, it might be a good idea to mention my proposedsys._is_immortal, so there's less ambiguity about the returned value.

cc@erlend-aasland

Has this already been discussed elsewhere?

No response given

Links to previous discussion of this feature:

No response

Linked PRs

• gh-128509: Addsys._is_immortal for identifying immortal objects #128510
• gh-128509: AddPyUnstable_IsImmortal for finding immortal objects #129182