Re: [Vcs-fast-import-devs] What's cooking in git.git (Oct 2009, #01; Wed, 07)

From: Sverre Rabbelier <srabbelier@gmail.com>
Date: Oct 30, 2009, 12:41 UTC
Message-ID: <fabb9a1e0910300541w40d17242rbf0683654d97457f@mail.gmail.com>
In-Reply-To: <4AEA626D.8060804@canonical.com>

Heya,

On Thu, Oct 29, 2009 at 20:50, Ian Clatworthy <ian.clatworthy@canonical.com> wrote:

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>> On Thu, Oct 8, 2009 at 19:39, Shawn O. Pearce <spearce@spearce.org> wrote:
> Sverre Rabbelier wrote:
>> [edited Shawn's message somewhat to be more relevant to vcs-fast-import-dev]
>
> Thanks Sverre. Before I start, sorry for taking so long to reply to this.

Thanks for the review :).

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> My strong preference is for:
>
> * feature = anything impacting semantics
> * option = tool-specific with no impact on semantics permitted.
>
> Both features and options ought to OS independent (where possible).

Even better, Shawn, if this LGTY I will reroll the series implementing this.

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>>> I think we want to declare features for import-marks and export-marks
>>> and define these as paths to local files which store a VCS specific
>>> formatted mapping of fast-import mark numbers to VCS labels.
>
> Explicitly specifying the local path names worries me though. Consider someone
> using fastimport tools to maintain multiple mirrors in different tools.
> What should the stream look like then? Does it need to change if we want
> an additional mirror.

I think the stream should not have to change, which works if you define the files to be local to the repo being exported to. That is, in git the line "feature export-marks=out.marks" would result in a marks file located in "/path/to/repo/.git/fast-import/out.marks". Or is that not what you mean?

> +1. By forcing tools to know about options specific to them, we avoid a
> range of bugs processing newer streams with older tools.

It is not possible to change the semantics using options though, what kind of bugs could arise this way?

> I don't think options should be permitted to change import behavior. In
> other words, we should actively discourage vcs-specific streams

Sounds fair, I reckon that a wiki in addition to the vcs-fast-import-devs list would not hurt :).

-- 
Cheers,

Sverre Rabbelier