Subject: Re: [PATCH 3/3] Revert "bash prompt: avoid command substitution when finalizing gitstring"

From: Junio C Hamano <[email-masked]>
Date: Wed, 21 Aug 2013 17:22:49 -0700

Brandon Casey <[email-masked]> writes:

> On Wed, Aug 21, 2013 at 2:47 PM, Junio C Hamano <[email-masked]> wrote:
>> Brandon Casey <[email-masked]> writes:
>>
>>> From: Brandon Casey <[email-masked]>
>>>
>>> This reverts commit 69a8141a5d81925b7e08cb228535e9ea4a7a02e3.
>>>
>>> Old Bash (3.0) which is distributed with RHEL 4.X and other ancient
>>> platforms that are still in wide use, does not have a printf that
>>> supports -v.  Let's revert this patch and go back to using printf
>>> in the traditional way.
>>>
>>> Signed-off-by: Brandon Casey <[email-masked]>
>>> ---
>>
>> Is this something you can detect at load-time once, store the result
>> in a private variable and then switch on it at runtime, something
>> along the lines of...
>>
>>
>>         # on load...
>>         printf -v __git_printf_supports_v -- "%s" yes >/dev/null 2>&1
>>
>>         ...
>>
>>         if test "${__git_printf_supports_v}" = yes
>>         then
>>                 printf -v gitstring -- "$printf_format" "$gitstring"
>>         else
>>                 gitstring=$(printf -- "$printf_format" "$gitstring")
>>         fi
>
> Yes, that appears to work.

A real patch needs to be a bit more careful, though.  The variable
needs to be cleared before all of the above, and the testing would
want to consider that the variable may not be set (i.e. use
"${var-}" when checking).

Thanks.

> -Brandon
>
>
>>>  contrib/completion/git-prompt.sh | 6 +-----
>>>  1 file changed, 1 insertion(+), 5 deletions(-)
>>>
>>> diff --git a/contrib/completion/git-prompt.sh b/contrib/completion/git-prompt.sh
>>> index a81ef5a..7698ec4 100644
>>> --- a/contrib/completion/git-prompt.sh
>>> +++ b/contrib/completion/git-prompt.sh
>>> @@ -433,11 +433,7 @@ __git_ps1 ()
>>>       local gitstring="$c${b##refs/heads/}${f:+$z$f}$r$p"
>>>
>>>       if [ $pcmode = yes ]; then
>>> -             if [[ -n ${ZSH_VERSION-} ]]; then
>>> -                     gitstring=$(printf -- "$printf_format" "$gitstring")
>>> -             else
>>> -                     printf -v gitstring -- "$printf_format" "$gitstring"
>>> -             fi
>>> +             gitstring=$(printf -- "$printf_format" "$gitstring")
>>>               PS1="$ps1pc_start$gitstring$ps1pc_end"
>>>       else
>>>               printf -- "$printf_format" "$gitstring"