On Mon, Nov 15 2021, Teng Long wrote:

Sometimes, we only want to get the objects from output of `ls-tree`
and commands like `sed` or `cut` is usually used to intercept the
origin output to achieve this purpose in practical.

The patch contains three commits

    1. Implementation of the option.
    2. Add new tests in "t3104".
    3. Documentation modifications.

I'm appreciate if someone help to review the patch.

I've looked it over, they look correct mostly, the test code in 2/3
looks a bit too complex (using find?).

But I'd much rather see this be done with adding strbuf_expand() to
ls-tree. I.e. its docs say that it can emit:

    <mode> SP <type> SP <object> TAB <file>

Or, with -l:

    <mode> SP <type> SP <object> SP <object size> TAB <file>

If you use strbuf_expand() you can just define a default format of:

    %(objectmode) SP %(objecttype) SP %(objectname) TAB %(path)

Then make the existing -l option a shorthand for tweaking that to:

    %(objectmode) SP %(objecttype) SP %(objectsize) SP %(objectname) TAB %(path)

Then you can get what you want out of this with a simple:

    git ls-tree --format="%(objectname)"

See e.g. git-cat-file for an existing use of strbuf_expand().