当试图使全屏glfw-window:不能将"glfw"借用为可变的，因为它也被借用为不可变的

Question

fn main() {
let mut glfw = glfw::init(glfw::FAIL_ON_ERRORS).unwrap();
// | Error occurs here
let (mut window, events) = glfw.with_primary_monitor(|_, m| {
glfw.create_window(300, 300, "Window",
m.map_or(glfw::WindowMode::Windowed, |m| glfw::WindowMode::FullScreen(m)))
}).expect("Failed to create GLFW window");
}

准确的错误是：

error[E0502]: cannot borrow `glfw` as mutable because it is also borrowed as immutable
--> src/main.rs:5:32
|
5 |       let (mut window, events) = glfw.with_primary_monitor(|_, m| {
|                                  ^    -------------------- ------ immutable borrow occurs here
|                                  |    |
|  ________________________________|    immutable borrow later used by call
| |
6 | |         glfw.create_window(300, 300, "Window",
| |         ---- first borrow occurs due to use of `glfw` in closure
7 | |             m.map_or(glfw::WindowMode::Windowed, |m| glfw::WindowMode::FullScreen(m)))
8 | |     }).expect("Failed to create GLFW window");
| |______^ mutable borrow occurs here

Answer 1

传递给with_primary_monitor中闭包的第一个参数是可以用来执行进一步操作的glfw对象。使用该参数可以使用glfw，而不是使用来自外部范围的参数：

let mut glfw = glfw::init(glfw::FAIL_ON_ERRORS).unwrap();
let (mut window, events) = glfw.with_primary_monitor(|glfw, m| {
glfw.create_window(300, 300, "Window",
m.map_or(glfw::WindowMode::Windowed, |m| glfw::WindowMode::FullScreen(m)))
}).expect("Failed to create GLFW window");