Re: [PATCH 0/2] cat-file: add a --stdin-cmd mode

> On Wed, Jan 19, 2022 at 05:58:40PM +0000, John Cai via GitGitGadget wrote:
>> I think this will be useful for other things, e.g. a not-trivial part of
>> "cat-file --batch" time is spent on parsing its argument and seeing if it's
>> a revision, ref etc.
>>
>> So we could e.g. add a command that only accepts a full-length 40 character
>> SHA-1, or switch the --format output mid-request etc.
>
> I would like to see a more concrete proposal or need for this sort of
> thing before we go too far down adding a new mode to a command so
> fundamental as cat-file is.

>
> Between your two proposals for other commands that you could add, I am
> not convinced that either of them needs to be in cat-file itself. IOW,
> you could easily inject another process in between which verifies that
> the provided objects are 40 character SHA-1s.
>
> The latter, changing the output format in-process, seems dubious to me.
> Is the start-up time of cat-file so slow (and you need to change formats
> so often) that the two together are unbearable? I'd be surprised if they
> were (and if so, we should focus our efforts on improving Git's start-up
> time).
>
> In the meantime, this is quite an invasive way to provide callers a way
> to control the output stream. If there really is a need to just force
> cat-file to flush more often, perhaps consider designating a special
> signal that we could treat as a request to flush the output stream?
>
> Thanks,
> Taylor