🦀 Rust -

Destructor / Finally

Rust doesn't have an official destructor or finally keyword, but it does have the Drop trait. The Drop trait is used to run code when a value goes out of scope.

Useful, but don't rely on it too much, like any finally block.

It is not guaranteed that the Drop will run.

• if a panicking thread panics again; e.g., in another destructor
• if running in -C panic=abort mode, no unwinding is done
• out of memory error leading to abort
• infinite loop exited with an abort
• power failure, etc.

struct FooFinally;

impl Drop for FooFinally {
    fn drop(&mut self) {
        println!("ah, finally!");
    }
}

fn bar() -> Result<(), ()> {
    let _finally = FooFinally;
    baz()?;
    Ok(())
}