Re: [RFC/PATCH V2] branch.c: replace git_config with git_config_get_string

[Eric Sunshine <sunshine@sunshineco.com>]

On Mon, Jun 23, 2014 at 6:41 AM, Tanay Abhra <tanayabh@gmail.com> wrote:
> Use git_config_get_string instead of git_config to take advantage of
> the config hash-table api which provides a cleaner control flow.
>
> Signed-off-by: Tanay Abhra <tanayabh@gmail.com>
> ---
>  branch.c | 24 ++++++++----------------
>  1 file changed, 8 insertions(+), 16 deletions(-)
>
> diff --git a/branch.c b/branch.c
> index 660097b..c9a2a0d 100644
> --- a/branch.c
> +++ b/branch.c
> @@ -140,33 +140,25 @@ static int setup_tracking(const char *new_ref, const char *orig_ref,
>         return 0;
>  }
>
> -struct branch_desc_cb {
> +struct branch_desc {
>         const char *config_name;
>         const char *value;
>  };

What is the purpose of retaining this structure? Following your
changes, it is never used outside of read_branch_desc(), and
'config_name' and 'value' would be more naturally declared as
variables local to that function.

> -static int read_branch_desc_cb(const char *var, const char *value, void *cb)
> -{
> -       struct branch_desc_cb *desc = cb;
> -       if (strcmp(desc->config_name, var))
> -               return 0;
> -       free((char *)desc->value);
> -       return git_config_string(&desc->value, var, value);
> -}
> -
>  int read_branch_desc(struct strbuf *buf, const char *branch_name)
>  {
> -       struct branch_desc_cb cb;
> +       const char *value = NULL;
> +       struct branch_desc desc;
>         struct strbuf name = STRBUF_INIT;
>         strbuf_addf(&name, "branch.%s.description", branch_name);
> -       cb.config_name = name.buf;
> -       cb.value = NULL;
> -       if (git_config(read_branch_desc_cb, &cb) < 0) {
> +       desc.config_name = name.buf;
> +       desc.value = NULL;
> +       git_config_get_string(desc.config_name, &value);
> +       if (git_config_string(&desc.value, desc.config_name, value) < 0) {

Although it works in this case, it's somewhat ugly that you ignore the
return value of git_config_get_string(), and a person reading the code
has to spend extra time digging into git_config_string() to figure out
why this is safe. If might be clearer for future readers by rephrasing
like this:

    if (git_config_get_string(desc.config_name, &value) < 0 ||
        git_config_string(&desc.value, desc.config_name, value) < 0) {

>                 strbuf_release(&name);
>                 return -1;
>         }
> -       if (cb.value)
> -               strbuf_addstr(buf, cb.value);
> +       strbuf_addstr(buf, desc.value);
>         strbuf_release(&name);
>         return 0;
>  }
> --
> 1.9.0.GIT