Does sort_by_key really need `'static` lifetime?

[dbarnett]

I hit a snag with lifetimes and wondered: is it intentional that WalkDir.sort_by_key requires a 'static lifetime on its func argument instead of just the same lifetime as the WalkDir?

I was trying to do something like this:

let walker = WalkDir::new(path)
    .sort_by_key(|e| {
        let relative_path = e.path().strip_prefix(path).unwrap();
        some_func(relative_path)
    })
    …

and that failed saying my path didn't live long enough for the required 'static lifetime, even though it does live until after walker was used and dropped.

[BurntSushi]

I would suggest putting path into an Arc. Either that, or just cloning it and moving it into the closure. Either should be marginal costs relative to recursive directory traversal.

[dbarnett]

Hmm, hate to ask but could you give an example? I tried something like:

    pub my_func<P: AsRef<Path> + Copy>(&mut self, path: P) {
        let path = Arc::new(path);
        let walker = WalkDir::new(path.clone().as_ref())
            .sort_by_key(move |e| {
                let relative_path = e.path().strip_prefix(path.clone().as_ref()).unwrap();
                some_func(relative_path)
            })
            …
    }

but I keep getting lifetime errors about "`P` may not live long enough ... for the static lifetime".

[BurntSushi]

Your Arc in that example looks like it has a lifetime attached to it. Make sure it has type Arc<PathBuf>.