Live manual Debian Live

# Debian Live Manual

# Estil de Codi

717

# 15. Estil de Codi

718

En aquest capítol es documenta l'estil de codi utilitzat a live systems.

719

15.1 Compatibilitat

720

- Avoid "bashisms", the codebase must be POSIX compliant and thus universally compatible.

721

- Furthermore it must comply with the version of the POSIX specification chosen by the current Debian Policy.

722

- Es pot comprovar els scripts amb 'sh -n' i 'checkbashisms'.

723

- Assegurar-se que tot el codi funciona amb 'set -e'.

724

15.2 Indentació

725

- Utilitzar sempre tabuladors en lloc d'espais.

726

- Keep case branch terminators (";;") aligned with the "content" of the branch, rather than the branch "entry".

727

Bé:

728

case "${1}" in
foo)
foobar
;;
bar)
foobar
;;
esac

729

15.3 Ajust de línia

730

- Generally, lines should be 80 chars at maximum.

731

- Placement of keywords like `then` and `do` should be chosen with good judgement with respect to clutter and readability. For small bits of code in particular it should be preferred to have them on the same line as the prior keyword they relate to (`if`; `for`; etc). Only place on the next line where it makes good sense to do so; typically this might only be to comply with maximum line length restrictions. One situation where they should always be placed on the next line is where what they follow is broken up onto multiple lines, and thus it being on a new line creates clear separation between that and the body of code following it. I.e. :

732

Preferred:

733

if foo; then
bar
fi
for FOO in $ITEMS; do
bar
done
if [ "${MY_LOCATION_VARIABLE}" = "something" ] && [ -e "${MY_OUTPUT_FILE}" ]
then
MY_OTHER_VARIABLE="$(some_bin ${FOOBAR} | awk -F_ '{ print $1 }')"
fi
if [ "${MY_FOO}" = "something" ] && [ -e "path/${FILE_1}" ] ||
[ "${MY_BAR}" = "something_else" ] && [ ${ALLOW} = "true" ]
then
foobar
fi

734

Less ideal:

735

if [ "${MY_LOCATION_VARIABLE}" = "something" ] && [ -e "${MY_OUTPUT_FILE}" ]; then
MY_OTHER_VARIABLE="$(some_bin ${FOOBAR} | awk -F_ '{ print $1 }')"
fi

736

Horrible:

737

if [ "${MY_LOCATION_VARIABLE}" = "something" ] && [ -e "${MY_OUTPUT_FILE}" ] || [ "${MY_LOCATION_VARIABLE}" = "something-else" ] && [ -e "${MY_OUTPUT_FILE_2}" ]; then
MY_OTHER_VARIABLE="$(some_bin ${FOOBAR} | awk -F_ '{ print $1 }')"
fi

738

- Prefer placing the opening brace of a function on a new line (for consistency with established style), and keep the braces aligned with the function name:

739

Bé:

740

Foo ()
{
bar
}

741

Bad (inconsistent with existing style):

742

Foo () {
bar
}

743

Awful:

744

Foo ()
{
bar
}

745

15.4 Variables

746

- Les variables van sempre en majúscules.

747

- Config variables used in live-build should start with an `LB_` prefix.

748

- Local function variables should be restricted to local scope.

749

- Les variables en relació a un paràmetre d'arrencada de live-config comencen amb `LIVE_`.

750

- Totes les altres variables de live-config comencen amb el prefix `_`

751

- Utilitzar claus al voltant de les variables, per exemple, escriure `${FOO}` en lloc de `$FOO`.

752

- Always protect variables with quotes to respect potential whitespaces (except where necessary to achieve correct word splitting): write `"${FOO}"` not `${FOO}`.

753

- Per raons de coherència, utilitzar sempre cometes al assignar valors a les variables:

754

Mal:

755

FOO=bar

756

Bé:

757

FOO="bar"

758

- If multiple variables are used, prefer quoting the full expression:

759

Typically bad:

760

if [ -f "${FOO}"/foo/"${BAR}"/bar ]; then
foobar
fi

761

Bé:

762

if [ -f "${FOO}/foo/${BAR}/bar" ]; then
foobar
fi

763

15.5 Miscel·lània

764

- Prefer "`|`" (without the surround quotes) as a separator in calls to sed, e.g. "`sed -e 's|foo|bar|'`" (without "").

765

- Don't use the `test` command for comparisons or tests, use "`[`" and "`]`" (without ""); e.g. "`if [ -x /bin/foo ]; ...`" and not "`if test -x /bin/foo; ...`".

766

- Use `case` wherever it makes code more readable than conditional checks (`if foo; ...` and tests without the actual `if` keyword, e.g. `[ -e "${FILE}" ] || exit 0`).

767

- Use "Foo_bar" style names for functions, i.e. a capital first letter, then all lowercase, with sensible use of underscores for better readability.