Re: [PATCH] Add __git_ps1_pc to use as PROMPT_COMMAND

[Michael J Gruber <git@drmicha.warpmail.net>]

Junio C Hamano venit, vidit, dixit 01.10.2012 23:09:
> Simon Oosthoek <s.oosthoek@xs4all.nl> writes:
> 
>> It's possible to set PS1 to nothing and print a string from
>> PROMPT_COMMAND, but then you miss out on all the features of the PS1
>> interpretation by bash and compared to the use of __git_ps1 at the
>> moment, it has to put out quite a different string. Because if you like
>> to see user@host+workdir (git-status)[$#]
>> the current users of __git_ps1 say PS1="\u@host+\w $(__git_ps1 "%s")\$
>> ", but all __git+ps1 has to put out is "(branch)" or "(branch *)", etc.
>>
>> If it has to print the same prompt in PC mode, it has to add all the
>> user/host/workdir/[$#] data as well, withouth being able to use the bash
>> internal interpretation (because that is only working when PS1 is set).
> 
> The longer I read your explanation, the less useful the "PC mode"
> sounds like, at least to me.  So why does an user even want to use
> such a mechanism, instead of PS1?  And even if the user wants to use
> it by doing \w, \u etc. himself, she can do that with
> 
> 	PROMPT_COMMAND='
> 		PS1=$(printf "\u \h \w %s$ " $(__git_ps1 "%s"))
>         '
> 
> just fine, no?
> 
> So I still do not see the problem, even taking your "Set PS1 in the
> command, without spitting anything out of the command" use case into
> account.
> 
> Confused....
> 

The "problem" (as far as I see) is only: What user interface do we want
to expose to the user, or rather, do we want to expose the user to ;)

So far, we say:

#    1) Copy this file to somewhere (e.g. ~/.git-prompt.sh).
#    2) Add the following line to your .bashrc/.zshrc:
#        source ~/.git-prompt.sh
#    3) Change your PS1 to also show the current branch:
#         Bash: PS1='[\u@\h \W$(__git_ps1 " (%s)")]\$ '
#         ZSH:  PS1='[%n@%m %c$(__git_ps1 " (%s)")]\$ '

(That's incomplete for zsh, but I'm digressing...). With the above, we
would change the bash instruction to

PROMPT_COMMAND='
	PS1=$(printf "\u \h \w %s$ " $(__git_ps1 "%s"))
       '

which may look more complicated to some. I think we can aim for
something like

PROMPT_COMMAND='__git_ps1_color "\u \h \w%s$ " " (%s)"'

so that the first arg is a PS1 string, %s there gets replaced by the git
prompt (if any), and the second arg defines the formatting of the git
prompt. This makes the "ui" (what you have to set the shells vars to) as
simple as possible.

As I said, I had done some fixes and refactoring to that effect already,
but I'm not going to race Simon.

Michael