Re: [Question] Can git cat-file have a type filtering option?

[Taylor Blau <me@ttaylorr.com>]

On Fri, Apr 07, 2023 at 09:30:18AM -0700, Junio C Hamano wrote:
> ZheNing Hu <adlternative@gmail.com> writes:
>
> > all blobs, and then use `git cat-file --batch` to retrieve them. This
> > is not very elegant, or in other words, it might be better to have an
> > internal implementation of filtering within `git cat-file
> > --batch-all-objects`.
>
> It does sound prominently elegant to have each tool does one task
> and does it well, and being able to flexibly combine them to achieve
> a larger task.

Yeah, agreed. It may be *convenient* to have an easy-to-reach option in
cat-file like '--exclude-type=tree,commit,tag' or something. But the
argument falls on a pretty slippery slope, as I think you note below.

> Is the object type the only thing that people often would want to
> base their filtering decision on?  Will we then see somebody else
> request a "--size-filter", and then somebody else realizes that the
> filtering criteria based on size need to be different between blobs
> (most likely counted in bytes) and trees (it may be more convenient
> to count the tree entries, not byes)?  It sounds rather messy and
> we may be better off having such an extensible logic in one place.
>
> Like rev-list's object list filtering, that is.

Yes, exactly. This definitely feels like a "do one thing and do it
well". `rev-list` is the tool we have for listing revisions and objects,
and it can produce output that is compatible with the kind of input that
other tools (like `cat-file`) can interpret.

Thanks,
Taylor