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doc: document current conventions on package naming

Mostly: encourage using dashes instead of underscores.
This commit is contained in:
Vladimír Čunát 2014-02-23 08:00:59 +01:00
parent 7f4b97d495
commit 1efb6e65d2

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@ -235,12 +235,7 @@ Most of the time, these are the same. For instance, the package
bound to the variable name <varname>e2fsprogs</varname> in
<filename>all-packages.nix</filename>, and the Nix expression is in
<filename>pkgs/os-specific/linux/e2fsprogs/default.nix</filename>.
However, identifiers in the Nix language dont allow certain
characters (e.g. dashes), so sometimes a different variable name
should be used. For instance, the
<literal>module-init-tools</literal> package is bound to the
<literal>module_init_tools</literal> variable in
<filename>all-packages.nix</filename>.</para>
</para>
<para>There are a few naming guidelines:
@ -261,17 +256,20 @@ should be used. For instance, the
a package named <literal>hello-svn</literal> by
<command>nix-env</command>.</para></listitem>
<listitem><para>Dashes in the package name should be changed to
underscores in variable names, rather than to camel case — e.g.,
<varname>module_init_tools</varname> instead of
<varname>moduleInitTools</varname>.</para></listitem>
<listitem><para>Dashes in the package name should be preserved
in new variable names, rather than converted to underscores
(which was convention up to around 2013 and most names
still have underscores instead of dashes) — e.g.,
<varname>http-parser</varname> instead of
<varname>http_parser</varname>.</para></listitem>
<listitem><para>If there are multiple versions of a package, this
should be reflected in the variable names in
<filename>all-packages.nix</filename>,
e.g. <varname>hello_0_3</varname> and <varname>hello_0_4</varname>.
e.g. <varname>json-c-0-9</varname> and <varname>json-c-0-11</varname>.
If there is an obvious “default” version, make an attribute like
<literal>hello = hello_0_4;</literal>.</para></listitem>
<literal>json-c = json-c-0-9;</literal>.
See also <xref linkend="sec-versioning" /></para></listitem>
</itemizedlist>
@ -288,7 +286,7 @@ dashes between words — not in camel case. For instance, it should be
<filename>allPackages.nix</filename> or
<filename>AllPackages.nix</filename>.</para>
<section><title>Hierachy</title>
<section><title>Hierarchy</title>
<para>Each package should be stored in its own directory somewhere in
the <filename>pkgs/</filename> tree, i.e. in
@ -567,7 +565,7 @@ splitting up an existing category.</para>
</section>
<section><title>Versioning</title>
<section xml:id="sec-versioning"><title>Versioning</title>
<para>Because every version of a package in Nixpkgs creates a
potential maintenance burden, old versions of a package should not be