another possible member of the Context trait about anyhow

[dtolnay]

Thanks! I would prefer not to add this for now, but you should be able to implement it in your codebase as an extension trait on top of anyhow::Context:

use anyhow::{Context, Result};
use std::fmt::Debug;
use std::fs;

pub trait ContextWith<T, E>: Context<T, E> {
    fn context_with(self, msg: &str, with: impl Debug) -> Result<T>;
}

impl<T, E, R> ContextWith<T, E> for R where R: Context<T, E> {
    fn context_with(self, msg: &str, with: impl Debug) -> Result<T> {
        self.with_context(|| format!("{} {:?}", msg, with))
    }
}

fn main() -> Result<()> {
    let path = "/nonexist";
    fs::read_to_string(&path).context_with("cannot open", &path)?;
    Ok(())
}

[stevedonovan]

In fact, just after I opened the issue I found I could add it anyway in this way, so I was happy.