从函数返回未来值 [英] Return Future value from a function

问题描述

我最近开始学习 Rust，但我不确定如何从应该返回 Result 的函数中返回未来值.当我尝试仅返回响应变量并删除结果输出时，出现错误:不能在返回 std::string::String 的函数中使用 ? 运算符

I recently started to learn Rust and I'm not sure how I can return future value from a function that should return a Result. When I try to return just the response variable and remove the Result output, I get an error: cannot use the ? operator in a function that returns std::string::String

#[tokio::main]
async fn download() -> Result<(),reqwest::Error> {
    let url = "https://query1.finance.yahoo.com/v8/finance/chart/TSLA";
    let response = reqwest::get(url)
                            .await?
                            .text()
                            .await?;
    Ok(response)
 }

我期望在 main() 中获取并打印响应值:

What I expect in main() is to get and print the response value:

fn main() {
    let response = download();
    println!("{:?}", response)
}

推荐答案

我想你的代码应该是这样的

I suppose your code should looks something like this

extern crate tokio; // 0.2.13

async fn download() -> Result<String, reqwest::Error> {
    let url = "https://query1.finance.yahoo.com/v8/finance/chart/TSLA";

    reqwest::get(url).await?.text().await
}

#[tokio::main]
async fn main() {
    let response = download().await;

    println!("{:?}", response)
}

这里是 rust 链接

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