Re: [PATCH] doc/cat-file: allow --use-mailmap for --batch options

[Christian Couder <christian.couder@gmail.com>]

On Sat, Oct 29, 2022 at 11:25 AM Siddharth Asthana
<siddharthasthana31@gmail.com> wrote:
>
> The command git cat-file can now use the mailmap mechanism to replace
> idents with their canonical versions for commit and tag objects. There
> are several options like `--batch`, `--batch-check` and
> `--batch-command` that can be combined with `--use-mailmap`. But, the
> documentation for `--batch`, `--batch-check` and `--batch-command`
> doesn't say so. This patch fixes that documentation.
>
> Mentored-by: Christian Couder <christian.couder@gmail.com>
> Mentored-by: John Cai <johncai86@gmail.com>
> Signed-off-by: Siddharth Asthana <siddharthasthana31@gmail.com>
> ---
>
> This patch was previously sent as the first patch of a 3 patch series for
> adding the mailmap support in git cat-file options:
> https://lore.kernel.org/git/20220916205946.178925-2-siddharthasthana31@gmail.com/

I think Taylor is probably right that there should be a version number
at the start of the subject line if the patch has already been sent
many times with the same subject and mostly the same content to the
list.

> Changes in v2:
> - Fixed the names in trailers in the commit message
> - Updated the documentation to clearly state that the `--batch-check`,
>   `--batch-command` and `--batch` options can only be used with
>   `--textconv`, `--filters` or `--use-mailmap`.
> - Fixed formatting
>
> Changes in v3:
> - Fixed formatting
>
> Changes in v4:
> - Fixed some grammatical errors

The version number should logically be "v4" according to the above.

>  Documentation/git-cat-file.txt | 45 ++++++++++++++++++++++++----------
>  1 file changed, 32 insertions(+), 13 deletions(-)
>
> diff --git a/Documentation/git-cat-file.txt b/Documentation/git-cat-file.txt
> index ec30b5c574..db2bba9b65 100644
> --- a/Documentation/git-cat-file.txt
> +++ b/Documentation/git-cat-file.txt
> @@ -89,26 +89,45 @@ OPTIONS
>  --batch::
>  --batch=<format>::
>         Print object information and contents for each object provided
> -       on stdin.  May not be combined with any other options or arguments
> -       except `--textconv` or `--filters`, in which case the input lines
> -       also need to specify the path, separated by whitespace.  See the
> -       section `BATCH OUTPUT` below for details.
> +       on stdin. May not be combined with any other options or arguments
> +       except --textconv, --filters, or --use-mailmap.
> +       +
> +       * When used with `--textconv` or `--filters`, the input lines
> +         must specify the path, separated by whitespace. See the section
> +         `BATCH OUTPUT` below for details.
> +       +
> +       * When used with `--use-mailmap`, the info command shows the size
> +         of the object as if the identities recorded in it were replaced
> +         by the mailmap mechanism.

Sorry to realize this only at this point but actually I think the
`info` command is only available when the `--batch-command` option is
used, not when the `--batch` option is used.

As the `--batch` option prints both object information (which includes
the size) and contents (which includes the idents), I think something
like the following should be used here:

       * When used with `--use-mailmap`, for commit and tag objects, the
          contents part of the output shows the identities replaced using the
          mailmap mechanism, while the information part of the output shows
          the size of the object as if it actually recorded the replacement
          identities.

>  --batch-check::
>  --batch-check=<format>::
> -       Print object information for each object provided on stdin.  May
> -       not be combined with any other options or arguments except
> -       `--textconv` or `--filters`, in which case the input lines also
> -       need to specify the path, separated by whitespace.  See the
> -       section `BATCH OUTPUT` below for details.
> +       Print object information for each object provided on stdin. May not be
> +       combined with any other options or arguments except --textconv, --filters
> +       or --use-mailmap.
> +       +
> +       * When used with `--textconv` or `--filters`, the input lines must
> +        specify the path, separated by whitespace. See the section
> +        `BATCH OUTPUT` below for details.
> +       +
> +       * When used with `--use-mailmap`, the info command shows the size
> +         of the object as if the identities recorded in it were replaced
> +         by the mailmap mechanism.

Same remark about the `info` command as above.

As the `--batch-check` option prints only object information (which
includes the size), I think something like the following should be
used here:

       * When used with `--use-mailmap`, for commit and tag objects, the
          printed object information shows the size of the object as if the
          identities recorded in it were replaced by the mailmap mechanism.

>  --batch-command::
>  --batch-command=<format>::
>         Enter a command mode that reads commands and arguments from stdin. May
> -       only be combined with `--buffer`, `--textconv` or `--filters`. In the
> -       case of `--textconv` or `--filters`, the input lines also need to specify
> -       the path, separated by whitespace. See the section `BATCH OUTPUT` below
> -       for details.
> +       only be combined with `--buffer`, `--textconv`, `--use-mailmap` or
> +       `--filters`.
> +       +
> +       * When used with `--textconv` or `--filters`, the input lines must
> +         specify the path, separated by whitespace. See the section
> +         `BATCH OUTPUT` below for details.
> +       +
> +       * When used with `--use-mailmap`, the info command shows the size
> +         of the object as if the identities recorded in it were replaced
> +         by the mailmap mechanism.

s/info command/`info` command/

And I think it could be interesting to add:

  - that it happens only for commits and tags, and
  - that when the `contents` command is used the idents are replaced.

So maybe something like:

       * When used with `--use-mailmap`, for commit and tag objects, the
         `contents` command shows the identities replaced using the
          mailmap mechanism, while the `info` command shows the size
          of the object as if it actually recorded the replacement
          identities.

Also this will become true only after your other patch series will be
merged. Which means that you should say somewhere that either

  - this patch should be merged only after the other patch series is merged, or
  - it's a bug that the `info` command doesn't show the size of the
updated object and this is going to be fixed soon by the other patch
series anyway.

Thanks for working on finishing this!
Christian.