/// Represents some struct that holds references inside
#[derive(Debug)]
struct MyValue<'a> {
    number: &'a u32,
}

/// There are many structs similar to `MyValue` and there is a
/// trait common to them all that can create them.
impl<'a> From<&'a u32> for MyValue<'a> {
    fn from(value: &'a u32) -> Self {
        MyValue {
            number: value,
        }
    }
}

/// This produces objects that hold references into it. So the
/// object must be dropped first before any new one is made.
trait Producer<'a, T: 'a> {
    fn make(&'a mut self) -> T;
}

struct MyProducer {
    number: u32,
}

impl MyProducer {
    fn new() -> Self {
        Self { number: 0 }
    }
}

impl<'a, T: 'a + From<&'a u32>> Producer<'a, T> for MyProducer {
    fn make(&'a mut self) -> T {
        self.number += 1;
        T::from(&self.number)
    }
}

fn main() {
    let mut producer = MyProducer::new();

    println!("made this: {:?}", <MyProducer as Producer<MyValue>>::make(&mut producer));
    println!("made this: {:?}", <MyProducer as Producer<MyValue>>::make(&mut producer));
}