How to retry an async func which has params?

[Zrs000]

I can retry functions like:

async fn test() -> Result<(), ()> {
    Ok(())
}

But how can I retry a function with a parameter like:

async fn test1(a: i32) -> Result<(), ()> {
    Ok(())
}

[Xuanwo]

Sadly, we don't have direct support for async func which has params (due to the limit of rust itself). The only possible way is to capture as a closure:

use anyhow::Result;
use backon::ExponentialBuilder;
use backon::Retryable;

async fn fetch(url: &str) -> Result<String> {
    Ok(reqwest::get(url).await?.text().await?)
}

#[tokio::main(flavor = "current_thread")]
async fn main() -> Result<()> {
    let content = (|| async { fetch("https://www.rust-lang.org").await })
        .retry(&ExponentialBuilder::default())
        .when(|e| e.to_string() == "retryable")
        .await?;

    println!("fetch succeeded: {}", content);
    Ok(())
}