get outside of filter (or allow +=ing into ext)

[remexre]

I'm trying to accumulate into a request extension; it'd be convenient to have either a non-filter way to get the current value of a request extension, or a way to "add into" request extensions that are... AddAssign? Extend? frunk::Semigroup?

[seanmonstar]

I don't quite follow, mind expanding?

[remexre]

Basically, either of:

fn get2<T: 'static + Clone + Send + Sync>() -> Option<T> {
    ::route::with(|route| route.extensions_mut().get(val).cloned())
}

// or

fn semigroup_append<T: 'static + Semigroup + Send + Sync>(t: T) {
    ::route::with(move |route| {
        let mut exts = route.extensions_mut();
        let val = exts.get::<T>()
            .map(|prev| prev.combine(&t))
            .unwrap_or(t);
        exts.insert(val);
    });
}

EDIT: With possibly AddAssign/Extend versions instead of Semigroup, to avoid a dependency on frunk.

[jxs]

this is now achievable with the Filter to Service conversion.
Also see #16 (comment)