// run-pass use std::mem::swap; #[derive(Debug)] struct Ints {sum: Box, values: Vec } fn add_int(x: &mut Ints, v: isize) { *x.sum += v; let mut values = Vec::new(); swap(&mut values, &mut x.values); values.push(v); swap(&mut values, &mut x.values); } fn iter_ints(x: &Ints, mut f: F) -> bool where F: FnMut(&isize) -> bool { let l = x.values.len(); (0..l).all(|i| f(&x.values[i])) } pub fn main() { let mut ints: Box<_> = Box::new(Ints {sum: Box::new(0), values: Vec::new()}); add_int(&mut *ints, 22); add_int(&mut *ints, 44); iter_ints(&*ints, |i| { println!("isize = {:?}", *i); true }); println!("ints={:?}", ints); }