hyper_util: How to add hyper_util::client::pool::map::Map to custom struct?

[hatoo]

Is your feature request related to a problem? Please describe.

I want use hyper_util::client::pool::map::Map as connection cache as http client.
Because of map::builder::Built<> is not exposed, we can't fill generics parameter of hyper_util::client::pool::map::Map so we can't add it custom struct.

Describe the solution you'd like

No idea

Additional context

I want create a struct of HTTP client like

pub struct Client {
    ...
    pub client_pool: hyper_util::client::pool::map::Map<????>,
}

But I can't. Is there any alternative?

[seanmonstar]

It currently cannot be named, that's correct. What I've done in reqwest, besides also wrapping it as a service, is to convert it into a trait object. Something like this:

let map_svc = service_fn(move |req| {
    let mut mapped = map.service(req.uri()).call(req.uri());
    async move {
        let mut svc = mapped.await?;
        svc.ready().await?;
        svc.call(req).await
    }
});

let pool_as_svc = tower::util::BoxService::new(map_svc);