rust - rust 生命周期参数必须超过静态生命周期

Question

因此，我遵循this tutorial构建类似流氓的行为，并决定开始使用specs调度程序来简化系统的注册和执行。

为此，我在Dispatcher结构中添加了 State :

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，当我尝试实现 GameSate 特征时，我遇到了问题:

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();
    }
}

我得到这些错误:

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

它希望生存期的'a, 'b超过'static的生存期，这听起来是不可能的，因为我确定'static是整个程序的生存期。

我该如何解决？

Answer 1

GameState 要求实现者必须为'static:

pub trait GameState: 'static {...}

为了满足'static的生命周期，您的类型不得包含任何比'static短的引用。因此，如果您不能同时将'a和'b都设为'static，则唯一的选择就是不要将Dispatcher放入State内。