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emtel • last Friday at 8:59 PM • 1 reply • view on HN

There are some situations with tricky lifetime issues that are almost impossible to write without this pattern. Trying to break code out into functions would force you to name all the types (not even possible for closures) or use generics (which can lead to difficulties specifying all required trait bounds), and `drop()` on its own is of no use since it doesn't effect the lexical lifetimes.

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nemo1618 • yesterday at 3:33 AM

Conversely, I use this "block pattern" a lot, and sometimes it causes lifetime issues:

    let foo: &[SomeType] = {
        let mut foo = vec![];
        // ... initialize foo ...
        &foo
    };
This doesn't work: the memory is owned by the Vec, whose lifetime is tied to the block, so the slice is invalid outside of that block. To be fair, it's probably best to just make foo a Vec, and turn it into a slice where needed.
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