rust - &self move field containing Box - Move out of borrowed content -

i have struct field containing references other structs (that did not define)

struct htmlhandlebars {     user_helpers: vec<(string, box<helperdef + 'static>)>, } 

and htmlhandlebars has implement function

fn render(&self, ...) -> &self 

and in function need move box function. this:

fn render(&self, ...) -> &self {     let mut handlebars = handlebars::new();     (name, helper) in self.user_helpers {         handlebars.register_helper(&name, helper);     } } 

but kind of stuck because:

• i can't move box references because borrowing self
• i can't copy box references because struct not implement copy
• i can't modify &self &mut self because causes other problems...

maybe doing wrong.. there else can do? options?

if need more complete overview of code, can find here

ps: had no idea how describe situation in title, feel free change it

the code you've written trying consume vec , elements. in general, can iterate on &self.user_helpers give references elements rather consuming them. (modulo silly typos in pattern):

for &(ref name, ref helper) in self.user_helpers {     handlebars.register_helper(name, helper); } 

see also: the rust programming language on iterating vectors.

there problem though: handlebars needs ownership of helpers. may have create new handlebars object every time render, in case need able create helpers every time create new handlebars. there no way take ownership of boxes without taking @ least &mut reference vec. need @ least mutable access take handlers out of struct. , if did that, wouldn't have handlers around next time render() called. depending on how configurable set of handlers is, have function constructs vec<box<helperdef + 'static>> out of thin air when need it, or maintain list of callbacks construct box<helperdef + 'static> you.