Re: [PATCH 1/2] Allow __git_ps1 to be used in PROMPT_COMMAND

From: Junio C Hamano <gitster@pobox.com>
Date: Oct 8, 2012, 21:17 UTC
Message-ID: <7v7gr0k6jv.fsf@alter.siamese.dyndns.org>
In-Reply-To: <50732EA1.7040608@xs4all.nl>

Simon Oosthoek <s.oosthoek@xs4all.nl> writes:

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> How about "This has advantages for using color without running
> into prompt-wrapping issues. Only by assigning \[ and \] to PS1
> directly can bash know these and the color codes in between don't
> count in the length of the prompt."?
>
> I'll rewrite the patch later on...
>
> Isn't it confusing that the color codes don't figure in this patch at all?

Since the "Subject:" is "allow ... to be used in PROMPT_COMMAND", it very much is relevant to mention that we need to use PROMPT_COMMAND in order to correctly use \[ and \] to generated zero-width escape sequences, which cannot be done by simply setting PS1 to command substitution.

"color" is just an example; if it makes you uneasy to say "color", you can say zero-width escape sequences. It could be \007 (BEL) ;-)

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> I don't think it would be possible to detect any other kind of
> customization without including specific code for it. Do you think it's
> unnecessary to include a warning? (I think it would take people a long
> time to figure out why their prompt goes whoopsy without getting a hint
> that PROMPT_COMMAND messes up the PS1)

I think you need your warning _only_ because you attempt to auto-detect it, when you do not have to.

> (OTOH, if you configure PROMPT_COMMAND, you're bound to know a little
> bit about what you're doing...)

Yup.