Matthew DeVore <matv...@google.com> writes:
> Add the following guideline to Documentation/CodingGuidelines:
>
> &&, ||, and | should appear at the end of lines, not the
> beginning, and the \ line continuation character should be
> omitted
"should be omitted" sounds as if it is the norm to have such a
character, but it is not. The text in the actual patch body does a
much better job than this.
Perhaps
Break overlong lines after "&&", "||", and "|", not before
them; that way the command can continue to subsequent lines
without backslash at the end.
> And the following to t/README (since it is specific to writing tests):
>
> pipes and $(git ...) should be avoided when they swallow exit
> codes of Git processes
Good.
> Signed-off-by: Matthew DeVore <matv...@google.com>
> ---
> Documentation/CodingGuidelines | 18 ++++++++++++++++++
> t/README | 28 ++++++++++++++++++++++++++++
> 2 files changed, 46 insertions(+)
>
> diff --git a/Documentation/CodingGuidelines b/Documentation/CodingGuidelines
> index 48aa4edfb..72967deb7 100644
> --- a/Documentation/CodingGuidelines
> +++ b/Documentation/CodingGuidelines
> @@ -118,6 +118,24 @@ For shell scripts specifically (not exhaustive):
> do this
> fi
>
> + - If a command sequence joined with && or || or | spans multiple
> + lines, put each command on a separate line and put && and || and |
> + operators at the end of each line, rather than the start. This
> + means you don't need to use \ to join lines, since the above
> + operators imply the sequence isn't finished.
Correct. Even though I wonder if we need to say the last sentence,
which is rather obvious, patch is already written and I do not see
much point editing this further.
> + (incorrect)
> + grep blob verify_pack_result \
> + | awk -f print_1.awk \
> + | sort >actual &&
> + ...
> +
> + (correct)
> + grep blob verify_pack_result |
> + awk -f print_1.awk |
> + sort >actual &&
> + ...
> +
> - We prefer "test" over "[ ... ]".
>
> - We do not write the noiseword "function" in front of shell
> diff --git a/t/README b/t/README
> index 85024aba6..9a71d5732 100644
> --- a/t/README
> +++ b/t/README
> @@ -466,6 +466,34 @@ And here are the "don'ts:"
> platform commands; just use '! cmd'. We are not in the business
> of verifying that the world given to us sanely works.
>
> + - Don't use Git upstream in the non-final position in a piped chain, as
> + in:
"upstream in the non-final position" is a bit redundant, isn't it?
- Don't feed the output of 'git' to a pipe, as in:
> +
> + git -C repo ls-files |
> + xargs -n 1 basename |
> + grep foo
> +
> + which will discard git's exit code and may mask a crash. In the
> + above example, all exit codes are ignored except grep's.
Good.
> + Instead, write the output of that command to a temporary
> + file with ">" or assign it to a variable with "x=$(git ...)" rather
> + than pipe it.
> +
> + - Don't use command substitution in a way that discards git's exit
> + code. When assigning to a variable, the exit code is not discarded,
> + e.g.:
> +
> + x=$(git cat-file -p $sha) &&
> + ...
> +
> + is OK because a crash in "git cat-file" will cause the "&&" chain
> + to fail, but:
> +
> + test "refs/heads/foo" = "$(git symbolic-ref HEAD)"
> +
> + is not OK and a crash in git could go undetected.
Good.
> - Don't use perl without spelling it as "$PERL_PATH". This is to help
> our friends on Windows where the platform Perl often adds CR before
> the end of line, and they bundle Git with a version of Perl that
