Re: [PATCH] technical doc: add a design doc for the evolve command

From: Jonathan Nieder <jrnieder@gmail.com>
Date: Nov 20, 2018, 22:06 UTC
Message-ID: <20181120220626.GB149929@google.com>
In-Reply-To: <CAPL8Zis6Jz3=Jb0JxuSyHczYQrrrqP3JGiov1ZuH2A_0x=dpVQ@mail.gmail.com>

Stefan Xenos wrote:

> On Tue, Nov 20, 2018 at 1:43 AM Ævar Arnfjörð Bjarmason
> <avarab@gmail.com> wrote:

Show 13 quoted lines

>> I think it sounds better to just make it, in the header:
>>
>>     x-evolve-pt content
>>     x-evolve-pt obsolete
>>     x-evolve-pt origin
>>
>> Where "pt = parent-type", we could of course spell that out too, but in
>> this case it's "x-evolve-pt" is the exact same number of bytes as
>> "parent-type", so nobody can object that it takes more space:)
>>
>> We'd then carry some documentation where we say everything except "x-*-"
>> is reserved, and that we'd like to know about new "*" there before it's
>> used, so it can be documented.

[...]

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>                                                      that should
> probably be the subject of a separate proposal (who owns the content
> of a namespace, what is the process for adding a new namespace or a
> new attribute within a namespace, what order should the header
> attributes appear in, what problem is namespacing there to solve, when
> do we use a namespaced attribute versus a "reserved" attribute, etc.).

Agreed. There are reasons that I prefer not to go in this direction, but regardless, it would be the subject of a separate thread if you want to pursue it.

>> Putting it in the commit message just sounds like a hack around not
>> having namespaced headers. If we'd like to keep this then tools would
>> need to parse both (potentially unpacking a lot of the commit message
>> object, it can be quite big in some cases...).

On the contrary: putting it in the commit message is a way to experiment with the workflow without changing the object format at all.

I don't think we should underestimate the value of that ability.

I don't understand what you're referring to by parsing both. Are you saying that if the experiment proves successful, we wouldn't be able to migrate completely to a new format? That sounds worrying to me --- I want the ability to experiment and to act on what we learn from an experiment, including when it touches on formats.

Thanks, Jonathan