commit 606bf6dc17b6cdc5217a27d9bc703bc0f43f8c58 · pyrox.dev/nixpkgs

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doc/functions.xml

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         The nixpkgs repository has several utility functions to manipulate Nix expressions.

     

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        </para>

     

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        <xi:include href="functions/library.xml" />

     

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        <xi:include href="functions/generators.xml" />

     

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        <xi:include href="functions/generators.section.xml" />

     

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        <xi:include href="functions/debug.section.xml" />

     

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        <xi:include href="functions/prefer-remote-fetch.section.xml" />

     

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        <xi:include href="functions/nix-gitignore.section.xml" />

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doc/functions/generators.section.md

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       # Generators {#sec-generators}

     

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       Generators are functions that create file formats from nix data structures, e. g. for configuration files. There are generators available for: `INI`, `JSON` and `YAML`

     

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       All generators follow a similar call interface: `generatorName configFunctions data`, where `configFunctions` is an attrset of user-defined functions that format nested parts of the content. They each have common defaults, so often they do not need to be set manually. An example is `mkSectionName ? (name: libStr.escape [ "[" "]" ] name)` from the `INI` generator. It receives the name of a section and sanitizes it. The default `mkSectionName` escapes `[` and `]` with a backslash.

     

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       Generators can be fine-tuned to produce exactly the file format required by your application/service. One example is an INI-file format which uses `: ` as separator, the strings `"yes"`/`"no"` as boolean values and requires all string values to be quoted:

     

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       ```nix

     

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       with lib;

     

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       let

     

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         customToINI = generators.toINI {

     

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           # specifies how to format a key/value pair

     

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           mkKeyValue = generators.mkKeyValueDefault {

     

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             # specifies the generated string for a subset of nix values

     

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             mkValueString = v:

     

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                    if v == true then ''"yes"''

     

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               else if v == false then ''"no"''

     

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               else if isString v then ''"${v}"''

     

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               # and delegats all other values to the default generator

     

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               else generators.mkValueStringDefault {} v;

     

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           } ":";

     

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         };

     

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       # the INI file can now be given as plain old nix values

     

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       in customToINI {

     

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         main = {

     

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           pushinfo = true;

     

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           autopush = false;

     

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           host = "localhost";

     

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           port = 42;

     

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         };

     

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         mergetool = {

     

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           merge = "diff3";

     

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         };

     

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       }

     

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       ```

     

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       This will produce the following INI file as nix string:

     

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       ```INI

     

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       [main]

     

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       autopush:"no"

     

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       host:"localhost"

     

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       port:42

     

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       pushinfo:"yes"

     

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       str\:ange:"very::strange"

     

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       [mergetool]

     

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       merge:"diff3"

     

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       ```

     

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       ::: note

     

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       Nix store paths can be converted to strings by enclosing a derivation attribute like so: `"${drv}"`.

     

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       :::

     

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       Detailed documentation for each generator can be found in `lib/generators.nix`.

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doc/functions/generators.xml

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       <section xmlns="http://docbook.org/ns/docbook"

     

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                xmlns:xlink="http://www.w3.org/1999/xlink"

     

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                xmlns:xi="http://www.w3.org/2001/XInclude"

     

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                xml:id="sec-generators">

     

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        <title>Generators</title>

     

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        <para>

     

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         Generators are functions that create file formats from nix data structures, e. g. for configuration files. There are generators available for: <literal>INI</literal>, <literal>JSON</literal> and <literal>YAML</literal>

     

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        </para>

     

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        <para>

     

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         All generators follow a similar call interface: <code>generatorName configFunctions data</code>, where <literal>configFunctions</literal> is an attrset of user-defined functions that format nested parts of the content. They each have common defaults, so often they do not need to be set manually. An example is <code>mkSectionName ? (name: libStr.escape [ "[" "]" ] name)</code> from the <literal>INI</literal> generator. It receives the name of a section and sanitizes it. The default <literal>mkSectionName</literal> escapes <literal>[</literal> and <literal>]</literal> with a backslash.

     

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        </para>

     

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        <para>

     

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         Generators can be fine-tuned to produce exactly the file format required by your application/service. One example is an INI-file format which uses <literal>: </literal> as separator, the strings <literal>"yes"</literal>/<literal>"no"</literal> as boolean values and requires all string values to be quoted:

     

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        </para>

     

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       <programlisting>

     

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       with lib;

     

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       let

     

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         customToINI = generators.toINI {

     

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           # specifies how to format a key/value pair

     

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           mkKeyValue = generators.mkKeyValueDefault {

     

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             # specifies the generated string for a subset of nix values

     

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             mkValueString = v:

     

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                    if v == true then ''"yes"''

     

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               else if v == false then ''"no"''

     

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               else if isString v then ''"${v}"''

     

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               # and delegats all other values to the default generator

     

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               else generators.mkValueStringDefault {} v;

     

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           } ":";

     

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         };

     

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       # the INI file can now be given as plain old nix values

     

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       in customToINI {

     

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         main = {

     

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           pushinfo = true;

     

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           autopush = false;

     

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           host = "localhost";

     

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           port = 42;

     

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         };

     

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         mergetool = {

     

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           merge = "diff3";

     

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         };

     

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       }

     

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       </programlisting>

     

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        <para>

     

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         This will produce the following INI file as nix string:

     

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        </para>

     

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       <programlisting>

     

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       [main]

     

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       autopush:"no"

     

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       host:"localhost"

     

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       port:42

     

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       pushinfo:"yes"

     

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       str\:ange:"very::strange"

     

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       [mergetool]

     

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       merge:"diff3"

     

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       </programlisting>

     

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        <note>

     

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         <para>

     

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          Nix store paths can be converted to strings by enclosing a derivation attribute like so: <code>"${drv}"</code>.

     

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         </para>

     

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        </note>

     

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        <para>

     

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         Detailed documentation for each generator can be found in <literal>lib/generators.nix</literal>.

     

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        </para>

     

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       </section>