Re: [PATCH 6/8] git-prompt: add fallback for shells without $'...'

Junio C Hamano
2024-07-23T20:25:27Z

"Avi Halachmi (:avih) via GitGitGadget" <gitgitgadget@gmail.com>
writes:

> From: "Avi Halachmi (:avih)" <avihpit@yahoo.com>
>
> $'...' is new in POSIX (2024), and some shells support it in recent
> versions, while others have had it for decades (bash, zsh, ksh93).

I will not look at this series futher during the current development
cycle that is about to conclude, but ...

> +__git_SOH=$'\1' __git_STX=$'\2' __git_ESC=$'\33'
> +__git_LF=$'\n' __git_CRLF=$'\r\n'
> +
> +if [ $'\101' != A ]; then # fallback for shells without $'...'
> + __git_CRLF=$(printf "\r\n\1\2\33") # CR LF SOH STX ESC
> + __git_ESC=${__git_CRLF#????}; __git_CRLF=${__git_CRLF%?}
> + __git_STX=${__git_CRLF#???}; __git_CRLF=${__git_CRLF%?}
> + __git_SOH=${__git_CRLF#??}; __git_CRLF=${__git_CRLF%?}
> + __git_LF=${__git_CRLF#?}
> +fi

... given that these are not used literally in-place but are always
referred to by their __git_BYTE names, if we are making this script
portable across shells to the same degree as other shell scripts
following our coding guidelines, I would prefer to see it done
without any "fallback".

$(printf '\r') would work with bash, zsh and ksh93, too, and one
time assignment to these variables is not going to be performance
critical. Just forbid use of $'\octal' notation in the coding
guidelines document, and implement just one variant.

Perhaps we should spell more things out that you wrote in some of
your proposed log messages more explicitly. I think these have been
rules we have followed (grep for them in *.sh files outside
contrib/) but I did not find mention in the guidelines document.

Thanks.

Documentation/CodingGuidelines | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git c/Documentation/CodingGuidelines w/Documentation/CodingGuidelines
index 1d92b2da03..bb058fcc87 100644
--- c/Documentation/CodingGuidelines
+++ w/Documentation/CodingGuidelines
@@ -107,6 +107,8 @@ For shell scripts specifically (not exhaustive):

- We do not use Process Substitution <(list) or >(list).

+ - We do not use Dollar-Single-Quotes $'<octal>' notation.
+
- Do not write control structures on a single line with semicolon.
"then" should be on the next line for if statements, and "do"
should be on the next line for "while" and "for".
@@ -140,7 +142,8 @@ For shell scripts specifically (not exhaustive):
sort >actual &&
...

- - We prefer "test" over "[ ... ]".
+ - We prefer "test" over "[ ... ]". Never use "[[ ... ]]" unless in a
+ script only meant for bash.

- We do not write the noiseword "function" in front of shell
functions.