rust 生命周期参数必须比静态生命周期长 [英] rust lifetime parameter must outlive the static lifetime

问题描述

所以我正在关注 本教程 来构建一个类似 rogue 的游戏，我已经决定开始使用规范调度器来简化系统的注册和执行.

So I'm following this tutorial to build a rogue-like and I've decided to start using the specs dispatcher to make registering and executing systems a bit easier.

为此，我添加了一个 Dispatcher 到我的 State 结构:

To do that I've added a Dispatcher to my State struct:

use rltk::{GameState, Rltk};
use specs::world::World;
use specs::Dispatcher;


pub struct State<'a, 'b> {  // <-- Added new lifetime params here for dispacher
    pub ecs: World,
    pub dsp: Dispatcher<'a, 'b>,
}

但是当我尝试实施 GameSate 它的特征我遇到了问题:

But it's when I try to implement the GameSate trait for it I run into issues:

impl<'a, 'b> GameState for State<'a, 'b> {
    fn tick(&mut self, ctx: &mut Rltk) {
        ctx.cls();
        self.dsp.dispatch(&mut self.ecs);
        self.ecs.maintain();
    }
}

我收到这些错误:

error[E0478]: lifetime bound not satisfied
  --> src/sys/state.rs:96:14
   |
96 | impl<'a, 'b> GameState for State<'a, 'b> {
   |              ^^^^^^^^^
   |
note: lifetime parameter instantiated with the lifetime `'a` as defined on the impl at 96:6
  --> src/sys/state.rs:96:6
   |
96 | impl<'a, 'b> GameState for State<'a, 'b> {
   |      ^^
   = note: but lifetime parameter must outlive the static lifetime

error[E0478]: lifetime bound not satisfied
  --> src/sys/state.rs:96:14
   |
96 | impl<'a, 'b> GameState for State<'a, 'b> {
   |              ^^^^^^^^^
   |
note: lifetime parameter instantiated with the lifetime `'b` as defined on the impl at 96:10
  --> src/sys/state.rs:96:10
   |
96 | impl<'a, 'b> GameState for State<'a, 'b> {
   |          ^^
   = note: but lifetime parameter must outlive the static lifetime

它希望 'a, 'b 的生命周期长于 'static，这听起来不可能，因为我确信 'static 是整个程序的生命周期.

It wants the lifetimes 'a, 'b to outlive 'static, which sounds impossible as I'm sure that 'static is the whole program's lifetime.

我该如何解决这个问题?

How do I resolve this?

推荐答案

GameState 要求实现者必须是 'static:

pub trait GameState: 'static {...}

为了满足 'static 生存期，您的类型不得包含任何短于 'static 的引用.所以，如果你不能让 'a 和 'b 都成为 'static，唯一的选择就是不要把 State 中的 Dispatcher.

In order to satisfy the 'static lifetime, your type must not contain any references shorter than 'static. So, if you can't make 'a and 'b both be 'static, the only option is not to put the Dispatcher inside State.

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