如何用`RefCell <vec <weak <gadget>＆gt;＆gt;`字段类型实现Debug到struct？

Question

代码：

struct Owner {
    name: String,
    gadgets: RefCell<Vec<Weak<Gadget>>>,
}

//code omitted

impl fmt::Debug for Owner {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "Owner {{ name: {}, gadgets: {:?} }}", self.name, self.gadgets.into_inner())
    }
}

fn main() {
    let gadget_owner : Rc<Owner> = Rc::new( Owner { /**/ });
    let gadget1 = gadget_owner.make_gadget(1);
    println!("gadget1 is: {:?}", gadget1);
}

带来错误：

error: cannot move out of borrowed content [E0507]
src/main.rs:25         write!(f, "Owner {{ name: {}, gadgets: {:?} }}", self.name, self.gadgets.into_inner())
                                                                                   ^~~~

full code there

Answer 1

添加retreiving小工具ID

impl fmt::Debug for Owner {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        let gadgets = self.gadgets.borrow();
        let ids: Vec<i32> = gadgets.iter()
                                   .map(|ref x| {
                                       x.upgrade()
                                        .unwrap()
                                        .id
                                   })
                                   .collect();
        write!(f, "Owner {{ name: {}, gadgets: {:?} }}", self.name, ids)
    }
}

输出：

gadget1 is: Gadget { id: 1, owner: Owner { name: Gadget Man, gadgets: [1, 2] } }
gadget2 is: Gadget { id: 2, owner: Owner { name: Gadget Man, gadgets: [1, 2] } }

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