Re: [PATCH 2/4] git-prompt.sh: refactor colored prompt code

From: SZEDER Gábor <szeder@ira.uka.de>
Date: Jun 23, 2013, 14:51 UTC
Message-ID: <20130623145157.GN20052@goldbirke>
In-Reply-To: <CAOz-D1+LoAnoRLgnyRYtq5LQR32RyXp4RR2M5pPTaxaGcXM4yg@mail.gmail.com>

On Sat, Jun 22, 2013 at 01:45:38PM -0300, Eduardo D'Avila wrote:

Show 16 quoted lines

> 2013/6/22 Øystein Walle <oystwa@gmail.com>:
> > I've gotten the impression it's better to use tput to generate the escape
> > sequences instead of hardcoding them. So something like:
> >
> > local c_red='\['"$(tput setaf 1)"'\]'
> > local c_green='\['"$(tput setaf 2)"'\]'
> > local c_green='\['"$(tput setaf 4)"'\]'
> > local c_clear='\['"$(tput sgr0)"'\]'
> >
> > which is technically cleaner, if not visually.
> >
> > The problem with that approach is that tput will be run several times for
> > each prompt, so it would be best if the color variables were global. Another
> > thing is that you rely on tput being available.
> 
> Are there any guidelines regarding global shell script variables?

There are a couple of global variables in the completion script, they are all prefixed with "__git_", e.g. $__git_porcelain_commands. In the prompt script we don't have any global variables at the moment, but if we were to create some, then they should be prefixed similarly. Or perhaps with "__git_ps1_". Anyway, in case of a global variable I'd spell out "color" completely instead of abbreviating it as "c".

> I'm considering doing this:
>    __git_c_red="\[$(tput setaf 1 || echo -e '\e[31m')\]"
> which handles the case where tput is not available.

To me 'tput setaf 1' is just a little bit less greek than '\e[31m'.

I'm wary of relying on tput's availability. It's part of ncurses, which is an essential package in many (most? all?) linux distros, but I don't know how it is with other supported platforms. So I think we'd have to stick to the hard-coded escape sequences as a fallback anyway. And if we can't get rid of these escape sequences completely, then I don't really see the point of using tput, especially considering the additional delay that would be caused by fork()ing four subshells and fork()+exec()ing four external commands on Windows.

However, I don't know much about the caveats of terminals, so I can't judge the benefits of using tput instead of the escape sequences.

Gábor