feat: make RequestBuilder::request public

[Colerar]

#1212

[lucab]

@seanmonstar how do you feel about landing this enhancement? I do have a similar usecase to what is shown in #1212, and I'd be happy to see this PR merged (or some similar logic to reach into the inner Request from the builder).

[seanmonstar]

Hm. While it's slightly more of a dance, I think a different approach would be if you could "build" the request, and then turn it back into a builder. That would at least mean we don't have to give out a &Result<..>, essentially exposing the internals of the builder.

[lucab]

Thanks for the quick feedback, personally that alternative would work for me as well.
Just to be explicit, if I correctly understood your idea then we'd need two additional methods to split/reassemble the builder:

• RequestBuilder::build_split(self) -> (Client, Result<Request>)
• RequestBuilder::from_parts(Client, Request) -> Self

Or, alternatively to the build_split() above, use the existing build() plus a new clone_client() in order to obtain the inner Client.
(All names and signatures open to bikeshedding)

[seanmonstar]

Something to that effect, yes. The only thing that makes me hesitate is "splitting" out the client. Would you no longer have a client to send the built request with? Hm, I suppose you might not, since the builder so far has just bundled it with it...

[lucab]

In my case indeed I don't have otherwise access to the Client.
I think it's kinda common to expose hooks for external logic in the form of ext_hook(rb: RequestBuilder) -> RequestBuilder methods. One such example is the request_builder_hook on https://docs.rs/deno_fetch/0.115.0/deno_fetch/struct.Options.html.

[lucab]

I've posted an implementation of the alternative approach at #1770.

[lucab]

#1770 just landed (thanks @seanmonstar for the quick review!), I think this can be closed.