编译器在给出生命周期时要求struct的生命周期 [英] Compiler asking for lifetime in struct when lifetime is given

问题描述

我正在尝试在"SFML游戏开发"一书中编写示例，但是对于应该代表游戏世界的结构的生存期存在问题.错误如下:

I'm trying to write the examples in the book "SFML Game Development" but I'm having a problem with the lifetimes for the struct that's supposed to represent the game world. The error is as follows:

extern crate sfml;

use self::sfml::window::*;
use self::sfml::graphics::*;

pub struct Game<'s> {
    mWindow: RenderWindow,
    mPlayer: &'s CircleShape,
}

错误消息:

error[E0106]: missing lifetime specifier
 --> src/game.rs:8:18
  |
8 |     mPlayer: &'s CircleShape,
  |                  ^^^^^^^^^^^ expected lifetime parameter

为什么要给我一辈子?

推荐答案

为什么要给我一辈子?

Why is it asking for a lifetime if I have given it one?

因为您没有在需要的时间里使用它.仔细查看错误消息.它告诉您CircleShape缺少生命周期，而不是的引用(尽管这也是必需的).

Because you haven't given it the lifetime where it's needed. Look closely at the error message. It's telling you that CircleShape is missing a lifetime, not the reference to CircleShape (although that's also needed).

查看CircleShape的定义:

pub struct CircleShape<'s> { /* fields omitted */ }

已对其进行了生命周期参数化，因此您需要提供一个参数:

It has been parameterized by a lifetime, so you need to provide one:

pub struct Game<'s> {
    mWindow: RenderWindow,
    mPlayer: &'s CircleShape<'s>,
}

对于您的情况，是否正确，我不能说，但是应该编译.

Whether that's correct for your case, I can't say, but it should compile.

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