Multi-index operator attempt in rust

attempt.rs

mod Foo
{


use ::std::ops;


pub struct Bar<T>
{
    a: T,
}

impl<T> Bar<T>
{
    pub fn new(a: T) -> Bar<T>
    {
        Bar { a }
    }
}


pub struct BarHelper<'a, T, I>
    where Bar<T>: 'a
{
    idx: I,
    bar: &'a Bar<T>,
}

impl<'a> ops::Index<i32> for &'a Bar<i32>
{
    type Output = BarHelper<'a, i32, i32>;

    fn index(&self, idx: i32) -> Self::Output
    {
        BarHelper { idx, bar: &self }
    }
}

impl<'a> ops::Index<i32> for BarHelper<'a, i32, i32>
{
    type Output = i32;

    fn index(&self, idx: i32) -> Self::Output
    {
        self.bar.a * self.idx + idx
    }
}


} /* mod Foo */


use Foo::Bar;

fn main()
{
    let x = Bar::new(2 as i32);

    assert_eq!(x[3][4], 2*3 + 4);
}