CODEWITHSUNDEEP
rust
Slothie
Slothie

Reputation: 81

Is there a way to drop a static lifetime object in Rust?

When searching for an answer, I found this question, however there is no mention of static lifetime objects. Can the method mentioned in this answer (calling drop() on the object) be used for static lifetime objects?

I was imagining a situation like a linked list. You need to keep nodes of the list around for (potentially) the entire lifetime of the program, however you also may remove items from the list. It seems wasteful to leave them in memory for the entire execution of the program.

Thanks!

Upvotes: 5

Views: 3174

Answers (1)

user2722968
user2722968

Reputation: 16515

No. The very point of a static is that it's static: It has a fixed address in memory and can't be moved from there. As a consequence, everybody is free to have a reference to that object, because it's guaranteed to be there as long as the program is executing. That's why you only get to use a static in the form of a &'static-reference and can never claim ownership.

Besides, doing this for the purpose of memory conservation is pointless: The object is baked into the executable and mapped to memory on access. All that could happen is for the OS to relinquish the memory mapping. Yet, since the memory is never allocated from the heap in the first place, there is no saving to be had.

The only thing you could do is to replace the object using unsafe mutable access. This is both dangerous (because the compiler is free to assume that the object does not in fact change) and pointless, due to the fact that the memory can't be freed, as it's part of the executable's memory mapping.

Upvotes: 6

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