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author | Nikolay Amiantov <ab@fmap.me> | 2016-01-21 19:43:52 +0300 |
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committer | Nikolay Amiantov <ab@fmap.me> | 2016-01-21 19:47:53 +0300 |
commit | 9c1d8037c07340bd2b88645eeefb7cc30fc312a5 (patch) | |
tree | 33fcd57b3ee1d5c483824f23838b832e34a13808 /doc/stdenv.xml | |
parent | f727f815cb075f6ff466f8c8a02a275502709eec (diff) | |
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nixpkgs manual: add a section about passthru
Diffstat (limited to 'doc/stdenv.xml')
-rw-r--r-- | doc/stdenv.xml | 33 |
1 files changed, 33 insertions, 0 deletions
diff --git a/doc/stdenv.xml b/doc/stdenv.xml index 8df23c911522..bab4a8b292e4 100644 --- a/doc/stdenv.xml +++ b/doc/stdenv.xml @@ -247,6 +247,39 @@ genericBuild </variablelist> +<variablelist> + <title>Special variables</title> + + <varlistentry> + <term><varname>passthru</varname></term> + <listitem><para>This is an attribute set which can be filled with arbitrary + values. For example: + +<programlisting> +passthru = { + foo = "bar"; + baz = { + value1 = 4; + value2 = 5; + }; +} +</programlisting> + +</para> + + <para>Values inside it are not passed to the builder, so you can change + them without triggering a rebuild. However, they can be accessed outside of a + derivation directly, as if they were set inside a derivation itself, e.g. + <literal>hello.baz.value1</literal>. We don't specify any usage or + schema of <literal>passthru</literal> - it is meant for values that would be + useful outside the derivation in other parts of a Nix expression (e.g. in other + derivations). An example would be to convey some specific dependency of your + derivation which contains a program with plugins support. Later, others who + make derivations with plugins can use passed-through dependency to ensure that + their plugin would be binary-compatible with built program.</para></listitem> + </varlistentry> + +</variablelist> </section> |