Re: [PATCH v5] format-patch: allow a non-integral version numbers

From: Eric Sunshine <sunshine@sunshineco.com>
Date: Mar 16, 2021, 23:36 UTC
Message-ID: <CAPig+cQSUewNPNRP95HORKLUDCrRsmX==r_bEHacNEuTUMwFQA@mail.gmail.com>
In-Reply-To: <pull.885.v5.git.1615883137212.gitgitgadget@gmail.com>

On Tue, Mar 16, 2021 at 4:25 AM ZheNing Hu via GitGitGadget <gitgitgadget@gmail.com> wrote:

Show 29 quoted lines

> Usually we can only use `format-patch -v<n>` to generate integral
> version numbers patches, but sometimes a same fixup should be
> labeled as a non-integral version like `v1.1`, so teach `format-patch`
> to allow a non-integral version which may be helpful to send those
> patches.
>
> `<n>` can be any string, such as `-v1.1`.  In the case where it
> is a non-integral value, the "Range-diff" and "Interdiff"
> headers will not include the previous version.
>
> Signed-off-by: ZheNing Hu <adlternative@gmail.com>
> ---
> diff --git a/builtin/log.c b/builtin/log.c
> @@ -1662,13 +1662,19 @@ static void print_bases(struct base_tree_info *bases, FILE *file)
> +static const char *diff_title(struct strbuf *sb,
> +                             const char *reroll_count,
> +                             const char *generic,
> +                             const char *rerolled)
>  {
> +       int reroll_count_int = -1;
> +
> +       if (reroll_count)
> +               strtol_i(reroll_count, 10, &reroll_count_int);
> +       if (reroll_count_int <= 0)
>                 strbuf_addstr(sb, generic);
>         else /* RFC may be v0, so allow -v1 to diff against v0 */
> +               strbuf_addf(sb, rerolled, reroll_count_int - 1);
>         return sb->buf;
>  }

Thanks. The logic of this version is much easier to understand now that the number parsing has been moved into diff_title().

It may still be a bit confusing for someone reading this code to understand why you don't check the return value of strtol_i(). Therefore, it might be a good idea to add an /* in-code comment */ explaining why you don't check whether the parse succeeded or failed. However, if we rewrite the code like this:

    int v;
    if (reroll_count && !strtol_i(reroll_count, 10, &v))
        strbuf_addf(sb, rerolled, v - 1);
    else
        strbuf_addstr(sb, generic);
    return sb->buf;

then the logic becomes obvious, and we don't even need a comment. (Notice that I also shortened the variable name since the code is just as clear with a short name as with a long spelled out name such as "reroll_count_int".)