mirror of
https://github.com/NixOS/nixpkgs.git
synced 2024-11-18 19:51:17 +00:00
496 lines
16 KiB
XML
496 lines
16 KiB
XML
<chapter xmlns="http://docbook.org/ns/docbook"
|
||
xmlns:xlink="http://www.w3.org/1999/xlink"
|
||
xml:id="chap-conventions">
|
||
|
||
<title>Coding conventions</title>
|
||
|
||
|
||
<section><title>Syntax</title>
|
||
|
||
<itemizedlist>
|
||
|
||
<listitem><para>Use 2 spaces of indentation per indentation level in
|
||
Nix expressions, 4 spaces in shell scripts.</para></listitem>
|
||
|
||
<listitem><para>Do not use tab characters, i.e. configure your
|
||
editor to use soft tabs. For instance, use <literal>(setq-default
|
||
indent-tabs-mode nil)</literal> in Emacs. Everybody has different
|
||
tab settings so it’s asking for trouble.</para></listitem>
|
||
|
||
<listitem><para>Use <literal>lowerCamelCase</literal> for variable
|
||
names, not <literal>UpperCamelCase</literal>. TODO: naming of
|
||
attributes in
|
||
<filename>all-packages.nix</filename>?</para></listitem>
|
||
|
||
<listitem><para>Function calls with attribute set arguments are
|
||
written as
|
||
|
||
<programlisting>
|
||
foo {
|
||
arg = ...;
|
||
}
|
||
</programlisting>
|
||
|
||
not
|
||
|
||
<programlisting>
|
||
foo
|
||
{
|
||
arg = ...;
|
||
}
|
||
</programlisting>
|
||
|
||
Also fine is
|
||
|
||
<programlisting>
|
||
foo { arg = ...; }
|
||
</programlisting>
|
||
|
||
if it's a short call.</para></listitem>
|
||
|
||
<listitem><para>In attribute sets or lists that span multiple lines,
|
||
the attribute names or list elements should be aligned:
|
||
|
||
<programlisting>
|
||
# A long list.
|
||
list =
|
||
[ elem1
|
||
elem2
|
||
elem3
|
||
];
|
||
|
||
# A long attribute set.
|
||
attrs =
|
||
{ attr1 = short_expr;
|
||
attr2 =
|
||
if true then big_expr else big_expr;
|
||
};
|
||
|
||
# Alternatively:
|
||
attrs = {
|
||
attr1 = short_expr;
|
||
attr2 =
|
||
if true then big_expr else big_expr;
|
||
};
|
||
</programlisting>
|
||
|
||
</para></listitem>
|
||
|
||
<listitem><para>Short lists or attribute sets can be written on one
|
||
line:
|
||
|
||
<programlisting>
|
||
# A short list.
|
||
list = [ elem1 elem2 elem3 ];
|
||
|
||
# A short set.
|
||
attrs = { x = 1280; y = 1024; };
|
||
</programlisting>
|
||
|
||
</para></listitem>
|
||
|
||
<listitem><para>Breaking in the middle of a function argument can
|
||
give hard-to-read code, like
|
||
|
||
<programlisting>
|
||
someFunction { x = 1280;
|
||
y = 1024; } otherArg
|
||
yetAnotherArg
|
||
</programlisting>
|
||
|
||
(especially if the argument is very large, spanning multiple
|
||
lines).</para>
|
||
|
||
<para>Better:
|
||
|
||
<programlisting>
|
||
someFunction
|
||
{ x = 1280; y = 1024; }
|
||
otherArg
|
||
yetAnotherArg
|
||
</programlisting>
|
||
|
||
or
|
||
|
||
<programlisting>
|
||
let res = { x = 1280; y = 1024; };
|
||
in someFunction res otherArg yetAnotherArg
|
||
</programlisting>
|
||
|
||
</para></listitem>
|
||
|
||
<listitem><para>The bodies of functions, asserts, and withs are not
|
||
indented to prevent a lot of superfluous indentation levels, i.e.
|
||
|
||
<programlisting>
|
||
{ arg1, arg2 }:
|
||
assert system == "i686-linux";
|
||
stdenv.mkDerivation { ...
|
||
</programlisting>
|
||
|
||
not
|
||
|
||
<programlisting>
|
||
{ arg1, arg2 }:
|
||
assert system == "i686-linux";
|
||
stdenv.mkDerivation { ...
|
||
</programlisting>
|
||
|
||
</para></listitem>
|
||
|
||
<listitem><para>Function formal arguments are written as:
|
||
|
||
<programlisting>
|
||
{ arg1, arg2, arg3 }:
|
||
</programlisting>
|
||
|
||
but if they don't fit on one line they're written as:
|
||
|
||
<programlisting>
|
||
{ arg1, arg2, arg3
|
||
, arg4, ...
|
||
, # Some comment...
|
||
argN
|
||
}:
|
||
</programlisting>
|
||
|
||
</para></listitem>
|
||
|
||
<listitem><para>Functions should list their expected arguments as
|
||
precisely as possible. That is, write
|
||
|
||
<programlisting>
|
||
{ stdenv, fetchurl, perl }: <replaceable>...</replaceable>
|
||
</programlisting>
|
||
|
||
instead of
|
||
|
||
<programlisting>
|
||
args: with args; <replaceable>...</replaceable>
|
||
</programlisting>
|
||
|
||
or
|
||
|
||
<programlisting>
|
||
{ stdenv, fetchurl, perl, ... }: <replaceable>...</replaceable>
|
||
</programlisting>
|
||
|
||
</para>
|
||
|
||
<para>For functions that are truly generic in the number of
|
||
arguments (such as wrappers around <varname>mkDerivation</varname>)
|
||
that have some required arguments, you should write them using an
|
||
<literal>@</literal>-pattern:
|
||
|
||
<programlisting>
|
||
{ stdenv, doCoverageAnalysis ? false, ... } @ args:
|
||
|
||
stdenv.mkDerivation (args // {
|
||
<replaceable>...</replaceable> if doCoverageAnalysis then "bla" else "" <replaceable>...</replaceable>
|
||
})
|
||
</programlisting>
|
||
|
||
instead of
|
||
|
||
<programlisting>
|
||
args:
|
||
|
||
args.stdenv.mkDerivation (args // {
|
||
<replaceable>...</replaceable> if args ? doCoverageAnalysis && args.doCoverageAnalysis then "bla" else "" <replaceable>...</replaceable>
|
||
})
|
||
</programlisting>
|
||
|
||
</para></listitem>
|
||
|
||
</itemizedlist>
|
||
|
||
</section>
|
||
|
||
|
||
<section xml:id="sec-organisation"><title>File naming and organisation</title>
|
||
|
||
<para>Names of files and directories should be in lowercase, with
|
||
dashes between words — not in camel case. For instance, it should be
|
||
<filename>all-packages.nix</filename>, not
|
||
<filename>allPackages.nix</filename> or
|
||
<filename>AllPackages.nix</filename>.</para>
|
||
|
||
<para>Each package should be stored in its own directory somewhere in
|
||
the <filename>pkgs/</filename> tree, i.e. in
|
||
<filename>pkgs/<replaceable>category</replaceable>/<replaceable>subcategory</replaceable>/<replaceable>...</replaceable>/<replaceable>pkgname</replaceable></filename>.
|
||
Below are some rules for picking the right category for a package.
|
||
Many packages fall under several categories; what matters is the
|
||
<emphasis>primary</emphasis> purpose of a package. For example, the
|
||
<literal>libxml2</literal> package builds both a library and some
|
||
tools; but it’s a library foremost, so it goes under
|
||
<filename>pkgs/development/libraries</filename>.</para>
|
||
|
||
<para>When in doubt, consider refactoring the
|
||
<filename>pkgs/</filename> tree, e.g. creating new categories or
|
||
splitting up an existing category.</para>
|
||
|
||
<variablelist>
|
||
<varlistentry>
|
||
<term>If it’s used to support <emphasis>software development</emphasis>:</term>
|
||
<listitem>
|
||
<variablelist>
|
||
<varlistentry>
|
||
<term>If it’s a <emphasis>library</emphasis> used by other packages:</term>
|
||
<listitem>
|
||
<para><filename>development/libraries</filename> (e.g. <filename>libxml2</filename>)</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term>If it’s a <emphasis>compiler</emphasis>:</term>
|
||
<listitem>
|
||
<para><filename>development/compilers</filename> (e.g. <filename>gcc</filename>)</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term>If it’s an <emphasis>interpreter</emphasis>:</term>
|
||
<listitem>
|
||
<para><filename>development/interpreters</filename> (e.g. <filename>guile</filename>)</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term>If it’s a (set of) development <emphasis>tool(s)</emphasis>:</term>
|
||
<listitem>
|
||
<variablelist>
|
||
<varlistentry>
|
||
<term>If it’s a <emphasis>parser generator</emphasis> (including lexers):</term>
|
||
<listitem>
|
||
<para><filename>development/tools/parsing</filename> (e.g. <filename>bison</filename>, <filename>flex</filename>)</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term>If it’s a <emphasis>build manager</emphasis>:</term>
|
||
<listitem>
|
||
<para><filename>development/tools/build-managers</filename> (e.g. <filename>gnumake</filename>)</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term>Else:</term>
|
||
<listitem>
|
||
<para><filename>development/tools/misc</filename> (e.g. <filename>binutils</filename>)</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
</variablelist>
|
||
</listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term>Else:</term>
|
||
<listitem>
|
||
<para><filename>development/misc</filename></para>
|
||
</listitem>
|
||
</varlistentry>
|
||
</variablelist>
|
||
</listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term>If it’s a (set of) <emphasis>tool(s)</emphasis>:</term>
|
||
<listitem>
|
||
<para>(A tool is a relatively small program, especially one intented
|
||
to be used non-interactively.)</para>
|
||
<variablelist>
|
||
<varlistentry>
|
||
<term>If it’s for <emphasis>networking</emphasis>:</term>
|
||
<listitem>
|
||
<para><filename>tools/networking</filename> (e.g. <filename>wget</filename>)</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term>If it’s for <emphasis>text processing</emphasis>:</term>
|
||
<listitem>
|
||
<para><filename>tools/text</filename> (e.g. <filename>diffutils</filename>)</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term>If it’s a <emphasis>system utility</emphasis>, i.e.,
|
||
something related or essential to the operation of a
|
||
system:</term>
|
||
<listitem>
|
||
<para><filename>tools/system</filename> (e.g. <filename>cron</filename>)</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term>If it’s an <emphasis>archiver</emphasis> (which may
|
||
include a compression function):</term>
|
||
<listitem>
|
||
<para><filename>tools/archivers</filename> (e.g. <filename>zip</filename>, <filename>tar</filename>)</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term>If it’s a <emphasis>compression</emphasis> program:</term>
|
||
<listitem>
|
||
<para><filename>tools/compression</filename> (e.g. <filename>gzip</filename>, <filename>bzip2</filename>)</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term>If it’s a <emphasis>security</emphasis>-related program:</term>
|
||
<listitem>
|
||
<para><filename>tools/security</filename> (e.g. <filename>nmap</filename>, <filename>gnupg</filename>)</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term>Else:</term>
|
||
<listitem>
|
||
<para><filename>tools/misc</filename></para>
|
||
</listitem>
|
||
</varlistentry>
|
||
</variablelist>
|
||
</listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term>If it’s a <emphasis>shell</emphasis>:</term>
|
||
<listitem>
|
||
<para><filename>shells</filename> (e.g. <filename>bash</filename>)</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term>If it’s a <emphasis>server</emphasis>:</term>
|
||
<listitem>
|
||
<variablelist>
|
||
<varlistentry>
|
||
<term>If it’s a web server:</term>
|
||
<listitem>
|
||
<para><filename>servers/http</filename> (e.g. <filename>apache-httpd</filename>)</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term>If it’s an implementation of the X Windowing System:</term>
|
||
<listitem>
|
||
<para><filename>servers/x11</filename> (e.g. <filename>xorg</filename> — this includes the client libraries and programs)</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term>Else:</term>
|
||
<listitem>
|
||
<para><filename>servers/misc</filename></para>
|
||
</listitem>
|
||
</varlistentry>
|
||
</variablelist>
|
||
</listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term>If it’s a <emphasis>desktop environment</emphasis>
|
||
(including <emphasis>window managers</emphasis>):</term>
|
||
<listitem>
|
||
<para><filename>desktops</filename> (e.g. <filename>kde</filename>, <filename>gnome</filename>, <filename>enlightenment</filename>)</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term>If it’s an <emphasis>application</emphasis>:</term>
|
||
<listitem>
|
||
<para>A (typically large) program with a distinct user
|
||
interface, primarily used interactively.</para>
|
||
<variablelist>
|
||
<varlistentry>
|
||
<term>If it’s a <emphasis>version management system</emphasis>:</term>
|
||
<listitem>
|
||
<para><filename>applications/version-management</filename> (e.g. <filename>subversion</filename>)</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term>If it’s for <emphasis>video playback / editing</emphasis>:</term>
|
||
<listitem>
|
||
<para><filename>applications/video</filename> (e.g. <filename>vlc</filename>)</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term>If it’s for <emphasis>graphics viewing / editing</emphasis>:</term>
|
||
<listitem>
|
||
<para><filename>applications/graphics</filename> (e.g. <filename>gimp</filename>)</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term>If it’s for <emphasis>networking</emphasis>:</term>
|
||
<listitem>
|
||
<variablelist>
|
||
<varlistentry>
|
||
<term>If it’s a <emphasis>mailreader</emphasis>:</term>
|
||
<listitem>
|
||
<para><filename>applications/networking/mailreaders</filename> (e.g. <filename>thunderbird</filename>)</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term>If it’s a <emphasis>newsreader</emphasis>:</term>
|
||
<listitem>
|
||
<para><filename>applications/networking/newsreaders</filename> (e.g. <filename>pan</filename>)</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term>If it’s a <emphasis>web browser</emphasis>:</term>
|
||
<listitem>
|
||
<para><filename>applications/networking/browsers</filename> (e.g. <filename>firefox</filename>)</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term>Else:</term>
|
||
<listitem>
|
||
<para><filename>applications/networking/misc</filename></para>
|
||
</listitem>
|
||
</varlistentry>
|
||
</variablelist>
|
||
</listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term>Else:</term>
|
||
<listitem>
|
||
<para><filename>applications/misc</filename></para>
|
||
</listitem>
|
||
</varlistentry>
|
||
</variablelist>
|
||
</listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term>If it’s <emphasis>data</emphasis> (i.e., does not have a
|
||
straight-forward executable semantics):</term>
|
||
<listitem>
|
||
<variablelist>
|
||
<varlistentry>
|
||
<term>If it’s a <emphasis>font</emphasis>:</term>
|
||
<listitem>
|
||
<para><filename>data/fonts</filename></para>
|
||
</listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term>If it’s related to <emphasis>SGML/XML processing</emphasis>:</term>
|
||
<listitem>
|
||
<variablelist>
|
||
<varlistentry>
|
||
<term>If it’s an <emphasis>XML DTD</emphasis>:</term>
|
||
<listitem>
|
||
<para><filename>data/sgml+xml/schemas/xml-dtd</filename> (e.g. <filename>docbook</filename>)</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term>If it’s an <emphasis>XSLT stylesheet</emphasis>:</term>
|
||
<listitem>
|
||
<para>(Okay, these are executable...)</para>
|
||
<para><filename>data/sgml+xml/stylesheets/xslt</filename> (e.g. <filename>docbook-xsl</filename>)</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
</variablelist>
|
||
</listitem>
|
||
</varlistentry>
|
||
</variablelist>
|
||
</listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term>If it’s a <emphasis>game</emphasis>:</term>
|
||
<listitem>
|
||
<para><filename>games</filename></para>
|
||
</listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term>Else:</term>
|
||
<listitem>
|
||
<para><filename>misc</filename></para>
|
||
</listitem>
|
||
</varlistentry>
|
||
</variablelist>
|
||
|
||
</section>
|
||
|
||
</chapter>
|