rust - Store reference of struct in other struct -

i have 2 structs. app , item.

what want achieve store item in items vector of app struct passing mutable reference items constructor.

pub struct app<'a> {     items: vec<&'a item> }  impl<'a> app<'a> {     pub fn new() -> app<'a> {         app { items: vec::new() }     }     pub fn register_item(&mut self, item: &'a item) {         self.items.push(item);     } }  pub struct item;  impl item {     pub fn new(app: &mut app) -> item {         let item = item;         app.register_item(&item);         item     } }  fn main() {     let mut app = app::new();      let item = item::new(&mut app);; } 

the code thows following error:

test.rs:8:28: 8:32 error: `item` not live long enough test.rs:8         app.register_item(&item); 

is there way this?

while rc might correct use case, it's understand why getting error are. please read why can't store value , reference value in same struct? has more in-depth discussion why code cannot work as-is. simplified explanation follows.

let's @ constructor:

fn new(app: &mut app) -> item {     let item = item;     app.register_item(&item);     item } 

here, create new item on stack @ address. let's pretend address 0x1000. take address of item (0x1000) , store vec inside app. return item calling function, resides in different stack frame. means address of item change, means 0x1000 no longer guaranteed point valid item! how rust prevents making whole classes of memory errors!

i'd you'd see written as:

fn main() {     let item = item;     let mut app = app::new();     app.register_item(&item); } 

this have same problem if tried return app or item function, address change.

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if have straight-forward tree structure, i'd advocate letting parent nodes own children:

struct app {     items: vec<item> }  impl app {     fn new() -> app {         app { items: vec::new() }     }      fn register_item(&mut self, item: item) {         self.items.push(item);     } }  pub struct item;  fn main() {     let mut app = app::new();     app.register_item(item); }