commit 31be0b922d921fee8b7f81d8de2fb9f0c9ccbc3d · pyrox.dev/nixpkgs

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nixos/doc/manual/development/freeform-modules.section.md

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       # Freeform modules {#sec-freeform-modules}

     

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       Freeform modules allow you to define values for option paths that have

     

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       not been declared explicitly. This can be used to add attribute-specific

     

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       types to what would otherwise have to be `attrsOf` options in order to

     

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       accept all attribute names.

     

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       This feature can be enabled by using the attribute `freeformType` to

     

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       define a freeform type. By doing this, all assignments without an

     

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       associated option will be merged using the freeform type and combined

     

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       into the resulting `config` set. Since this feature nullifies name

     

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       checking for entire option trees, it is only recommended for use in

     

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       submodules.

     

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       ::: {#ex-freeform-module .example}

     

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       ::: {.title}

     

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       **Example: Freeform submodule**

     

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       :::

     

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       The following shows a submodule assigning a freeform type that allows

     

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       arbitrary attributes with `str` values below `settings`, but also

     

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       declares an option for the `settings.port` attribute to have it

     

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       type-checked and assign a default value. See

     

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       [Example: Declaring a type-checked `settings` attribute](#ex-settings-typed-attrs)

     

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       for a more complete example.

     

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       ```nix

     

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       { lib, config, ... }: {

     

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         options.settings = lib.mkOption {

     

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           type = lib.types.submodule {

     

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             freeformType = with lib.types; attrsOf str;

     

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             # We want this attribute to be checked for the correct type

     

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             options.port = lib.mkOption {

     

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               type = lib.types.port;

     

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               # Declaring the option also allows defining a default value

     

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               default = 8080;

     

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             };

     

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           };

     

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         };

     

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       }

     

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       ```

     

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       And the following shows what such a module then allows

     

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       ```nix

     

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       {

     

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         # Not a declared option, but the freeform type allows this

     

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         settings.logLevel = "debug";

     

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         # Not allowed because the the freeform type only allows strings

     

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         # settings.enable = true;

     

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         # Allowed because there is a port option declared

     

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         settings.port = 80;

     

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         # Not allowed because the port option doesn't allow strings

     

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         # settings.port = "443";

     

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       }

     

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       ```

     

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       :::

     

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       ::: {.note}

     

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       Freeform attributes cannot depend on other attributes of the same set

     

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       without infinite recursion:

     

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       ```nix

     

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       {

     

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         # This throws infinite recursion encountered

     

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         settings.logLevel = lib.mkIf (config.settings.port == 80) "debug";

     

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       }

     

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       ```

     

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       To prevent this, declare options for all attributes that need to depend

     

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       on others. For above example this means to declare `logLevel` to be an

     

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       option.

     

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       :::

-68

nixos/doc/manual/development/freeform-modules.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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               version="5.0"

     

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               xml:id="sec-freeform-modules">

     

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        <title>Freeform modules</title>

     

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        <para>

     

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         Freeform modules allow you to define values for option paths that have not been declared explicitly. This can be used to add attribute-specific types to what would otherwise have to be <literal>attrsOf</literal> options in order to accept all attribute names.

     

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        </para>

     

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        <para>

     

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         This feature can be enabled by using the attribute <literal>freeformType</literal> to define a freeform type. By doing this, all assignments without an associated option will be merged using the freeform type and combined into the resulting <literal>config</literal> set. Since this feature nullifies name checking for entire option trees, it is only recommended for use in submodules.

     

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        </para>

     

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        <example xml:id="ex-freeform-module">

     

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         <title>Freeform submodule</title>

     

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         <para>

     

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          The following shows a submodule assigning a freeform type that allows arbitrary attributes with <literal>str</literal> values below <literal>settings</literal>, but also declares an option for the <literal>settings.port</literal> attribute to have it type-checked and assign a default value. See <xref linkend="ex-settings-typed-attrs"/> for a more complete example.

     

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         </para>

     

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        <programlisting>

     

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       { lib, config, ... }: {

     

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         options.settings = lib.mkOption {

     

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           type = lib.types.submodule {

     

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             freeformType = with lib.types; attrsOf str;

     

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             # We want this attribute to be checked for the correct type

     

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             options.port = lib.mkOption {

     

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               type = lib.types.port;

     

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               # Declaring the option also allows defining a default value

     

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               default = 8080;

     

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             };

     

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           };

     

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         };

     

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       }

     

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        </programlisting>

     

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        <para>

     

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         And the following shows what such a module then allows

     

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        </para>

     

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        <programlisting>

     

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       {

     

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         # Not a declared option, but the freeform type allows this

     

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         settings.logLevel = "debug";

     

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         # Not allowed because the the freeform type only allows strings

     

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         # settings.enable = true;

     

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         # Allowed because there is a port option declared

     

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         settings.port = 80;

     

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         # Not allowed because the port option doesn't allow strings

     

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         # settings.port = "443";

     

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       }

     

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        </programlisting>

     

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        </example>

     

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        <note>

     

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         <para>

     

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          Freeform attributes cannot depend on other attributes of the same set without infinite recursion:

     

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       <programlisting>

     

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       {

     

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         # This throws infinite recursion encountered

     

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         settings.logLevel = lib.mkIf (config.settings.port == 80) "debug";

     

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       }

     

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       </programlisting>

     

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          To prevent this, declare options for all attributes that need to depend on others. For above example this means to declare <literal>logLevel</literal> to be an option.

     

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         </para>

     

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        </note>

     

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       </section>

+87

nixos/doc/manual/from_md/development/freeform-modules.section.xml

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       <section xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink" xml:id="sec-freeform-modules">

     

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         <title>Freeform modules</title>

     

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         <para>

     

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           Freeform modules allow you to define values for option paths that

     

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           have not been declared explicitly. This can be used to add

     

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           attribute-specific types to what would otherwise have to be

     

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           <literal>attrsOf</literal> options in order to accept all attribute

     

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           names.

     

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         </para>

     

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         <para>

     

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           This feature can be enabled by using the attribute

     

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           <literal>freeformType</literal> to define a freeform type. By doing

     

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           this, all assignments without an associated option will be merged

     

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           using the freeform type and combined into the resulting

     

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           <literal>config</literal> set. Since this feature nullifies name

     

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           checking for entire option trees, it is only recommended for use in

     

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           submodules.

     

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         </para>

     

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         <anchor xml:id="ex-freeform-module" />

     

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         <para>

     

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           <emphasis role="strong">Example: Freeform submodule</emphasis>

     

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         </para>

     

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         <para>

     

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           The following shows a submodule assigning a freeform type that

     

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           allows arbitrary attributes with <literal>str</literal> values below

     

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           <literal>settings</literal>, but also declares an option for the

     

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           <literal>settings.port</literal> attribute to have it type-checked

     

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           and assign a default value. See

     

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           <link linkend="ex-settings-typed-attrs">Example: Declaring a

     

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           type-checked <literal>settings</literal> attribute</link> for a more

     

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           complete example.

     

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         </para>

     

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         <programlisting language="bash">

     

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       { lib, config, ... }: {

     

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         options.settings = lib.mkOption {

     

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           type = lib.types.submodule {

     

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             freeformType = with lib.types; attrsOf str;

     

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             # We want this attribute to be checked for the correct type

     

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             options.port = lib.mkOption {

     

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               type = lib.types.port;

     

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               # Declaring the option also allows defining a default value

     

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               default = 8080;

     

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             };

     

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           };

     

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         };

     

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       }

     

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       </programlisting>

     

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         <para>

     

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           And the following shows what such a module then allows

     

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         </para>

     

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         <programlisting language="bash">

     

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       {

     

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         # Not a declared option, but the freeform type allows this

     

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         settings.logLevel = &quot;debug&quot;;

     

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       +
       

     

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         # Not allowed because the the freeform type only allows strings

     

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         # settings.enable = true;

     

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         # Allowed because there is a port option declared

     

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         settings.port = 80;

     

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         # Not allowed because the port option doesn't allow strings

     

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         # settings.port = &quot;443&quot;;

     

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       }

     

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       </programlisting>

     

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         <note>

     

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           <para>

     

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             Freeform attributes cannot depend on other attributes of the same

     

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             set without infinite recursion:

     

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           </para>

     

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           <programlisting language="bash">

     

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       {

     

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         # This throws infinite recursion encountered

     

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         settings.logLevel = lib.mkIf (config.settings.port == 80) &quot;debug&quot;;

     

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       }

     

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       </programlisting>

     

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           <para>

     

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             To prevent this, declare options for all attributes that need to

     

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             depend on others. For above example this means to declare

     

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             <literal>logLevel</literal> to be an option.

     

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           </para>

     

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         </note>

     

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       </section>