Re: [RFC PATCH 0/8] Git remote helpers to implement smart transports.

From: Junio C Hamano <gitster@pobox.com>
Date: Dec 2, 2009, 18:41 UTC
Message-ID: <7vk4x5fcbf.fsf@alter.siamese.dyndns.org>
In-Reply-To: <fabb9a1e0912021006x2905578bo16dbcaedc0d97bc6@mail.gmail.com>

Sverre Rabbelier <srabbelier@gmail.com> writes:

Show 5 quoted lines

>> Of course, I never understood why the backend should know the
>> implementation detail that it is based on cURL, so it would be even more
>> modular (at least by my definition) if there was no hard-coded mapping.
>
> Agreed.

I don't get this point at all.

Backend is _very_ aware of how it is implemented itself. Naming one implementation git-remote-http is to declare that "I am the one and only implementation of http handler" and forces another implementation of http handler, perhaps based on different toolkit than libcurl, to forever be a second class citizen that need to use name other than 'http'.

The "mapping" you two are calling "hard-coded" may be "hard-coded" but is a better kind of hard-coding than hard-coding "http" to "this particular implementation" implicitly like you two seem to be advocating. Think of it as having one extra layer of indirection.

When the second implementation of http handler proves to be better than the current one, we can flip the mapping, and anybody who were using "http://" to access some repository will automatically updated to use the new backend instead of the old one. With your scheme, you probably could change the name of the old "http" backend to "http-deprecated" and the new one from "second-class-citizen-http" to "http" to achieve a similar effect, but I do not think it is as nice as having one extra level of indirection.

> However, I am not convinced that we should do any magic to map
> "foo://" to git-remote-foo. On the other hand, I do think it makes
> sense to have something modular that allows "git-remote-http" to be
> implemented as a separate package that can be installed.

As I said, I do think modular is good, but I think what Dscho is advocating does not have much to achieve that goal.