Question

我正在尝试为Iron请求创建处理程序：

extern crate iron;
extern crate mount;

use iron::{Iron, Request, Response, IronResult, status};
use mount::Mount;
use iron::middleware::Handler;

struct Server {
    message: String
}

impl Server {
    pub fn start(&self){
        let mut mount = Mount::new();
        mount.mount("/", &self);
        Iron::new(mount).http("0.0.0.0:3000").unwrap();
    }
}

impl Handler for Server {
    fn handle(&self, _req: &mut Request) -> IronResult<Response>{
        Ok(Response::with((status::Ok, self.message)))
    }
}

fn main() {
    Server{message: "test".to_string()}.start();
}

但编译器响应是：

error[E0277]: the trait bound `for<'r, 'r, 'r> Server: std::ops::Fn<(&'r mut iron::Request<'r, 'r>,)>` is not satisfied
  --> src/main.rs:15:15
   |
15 |         mount.mount("/", &self);
   |               ^^^^^ trait `for<'r, 'r, 'r> Server: std::ops::Fn<(&'r mut iron::Request<'r, 'r>,)>` not satisfied
   |
   = note: required because of the requirements on the impl of `std::ops::FnOnce<(&mut iron::Request<'_, '_>,)>` for `&Server`
   = note: required because of the requirements on the impl of `iron::Handler` for `&&Server`

我无法理解Rust对我说的话。

Answer 1

这是您的问题的复制品;你能发现问题吗？

trait Foo {}

struct Bar;

impl Foo for Bar {}

impl Bar {
    fn thing(&self) {
        requires_bar(self);
    }
}

fn requires_bar<F>(foo: F) where F: Foo {}

fn main() {}

放弃？

你已经为你的结构实现了特性：

impl Handler for Server

但是，然后尝试使用对结构的引用的引用，不实现该特征：

pub fn start(&self) {
    // ...
    mount.mount("/", &self);
    // ...
}

这样就行不通了。您需要重构代码或实现特征以引用结构。

无法创建Iron处理程序，因为特征绑定了std :: ops :: Fn＆lt;（＆amp; mut iron :: Request）＆gt;不满意

1 个答案: