example.rs

struct Container {
    inner: u32,
}

impl<'a> Container {
    fn new() -> Self {
        Self { inner: 1 }
    }

    fn expensive_lookup(&'a self) -> &'a u32 {
        &self.inner
    }
}

struct PreCached<'a> {
    container: Container,
    value: &'a u32
}

fn create<'a>() -> PreCached<'a> {
    let container = Container::new();
    let value = container.expensive_lookup();
    PreCached { container, value: &value }
}