Re: [PATCH v2 03/18] ref-filter: make valid_atom as function parameter

["Оля Тележная" <olyatelezhnaya@gmail.com>]

2018-01-18 1:39 GMT+03:00 Christian Couder <christian.couder@gmail.com>:
> On Wed, Jan 17, 2018 at 10:43 PM, Jeff King <peff@peff.net> wrote:
>> On Tue, Jan 16, 2018 at 09:55:22AM +0300, Оля Тележная wrote:
>>
>>> > IOW, the progression I'd expect in a series like this is:
>>> >
>>> >   1. Teach ref-filter.c to support everything that cat-file can do.
>>> >
>>> >   2. Convert cat-file to use ref-filter.c.
>>>
>>> I agree, I even made this and it's working fine:
>>> https://github.com/git/git/pull/450/commits/1b74f1047f07434dccb207534d1ad45a143e3f2b
>
> (Nit: it looks like the above link does not work any more, but it
> seems that you are talking about the last patch on the catfile
> branch.)
>
>>> But I decided not to add that to patch because I expand the
>>> functionality of several commands (not only cat-file and
>>> for-each-ref), and I need to support all new functionality in a proper
>>> way, make these error messages, test everything and - the hardest one
>>> - support many new commands for cat-file. As I understand, it is not
>>> possible unless we finally move to ref-filter and print results also
>>> there. Oh, and I also need to rewrite docs in that case. And I decided
>>> to apply this in another patch. But, please, say your opinion, maybe
>>> we could do that here in some way.
>>
>> Yeah, I agree that it will cause changes to other users of ref-filter,
>> and you'd need to deal with documentation and tests there. But I think
>> we're going to have to do those things eventually (since supporting
>> those extra fields everywhere is part of the point of the project). And
>> by doing them now, I think it can make the transition for cat-file a lot
>> simpler, because we never have to puzzle over this intermediate state
>> where only some of the atoms are valid for cat-file.
>
> I agree that you will have to deal with documentation and tests at one
> point and that it could be a good idea to do that now.
>
> I wonder if it is possible to add atoms one by one into ref-filter and
> to add tests and documentation at the same time, instead of merging
> cat-file atoms with ref-filter atoms in one big step.
>
> When all the cat-file atoms have been added to ref-filter's
> valid_atom, maybe you could add ref-filter's atoms to cat-file's
> valid_cat_file_atom one by one and add tests and documentation at the
> same time.
>
> And then when ref-filter's valid_atom and cat-file's
> valid_cat_file_atom are identical you can remove cat-file's
> valid_cat_file_atom and maybe after that rename "ref-filter" to
> "format".

I think it's important to finish migrating process at first. I mean,
now we are preparing and collecting everything in ref-filter, but we
make resulting string and print still in cat-file. And I am not sure,
but maybe it will not be possible to start using new atoms in cat-file
while some part of logic still differs.
And another thoughts here - we were thinking about creating format.h
but decided not to move forward with it, and now we are suffering
because of it. Can I create it right now or the history of commits
would be too dirty because of it? Also, do you mean just renaming of
ref-filter? I was thinking that I need to put formatting-related logic
to another file and leave all other stuff in ref-filter.

Anyway, your suggested steps looks good, and I am planning to
implement them later. Let's discuss, what behavior we are waiting for
when atom seems useless for the command. Die or ignore? And, which
atoms are useless (as I understand, "rest" and "deltabase" from
cat-file are useless for all ref-filter users, so the question is
about - am I right in it, and about ref-filter atoms for cat-file).

I have never written any tests and docs for Git, I will try to explore
by myself how to do that, but if you have any special links/materials
about it - please send them to me :)

Olga