···

       
18
       
 
       
  tab settings so it’s asking for trouble.</para></listitem>

     

       
19
       
 
       


     

       
20
       
 
       
  <listitem><para>Use <literal>lowerCamelCase</literal> for variable

     

       
21
       
-
       
  names, not <literal>UpperCamelCase</literal>.  TODO: naming of

     

       
22
       
-
       
  attributes in

     

       
23
       
-
       
  <filename>all-packages.nix</filename>?</para></listitem>

     

       
24
       
 
       


     

       
25
       
 
       
  <listitem><para>Function calls with attribute set arguments are

     

       
26
       
 
       
  written as

     
···

       
220
       
 
       


     

       
221
       
 
       
  <listitem><para>The variable name used for the instantiated package

     

       
222
       
 
       
  in <filename>all-packages.nix</filename>, and when passing it as a

     

       
223
       
-
       
  dependency to other functions.  This is what Nix expression authors

     

       
224
       
-
       
  see.  It can also be used when installing using <command>nix-env

     

       
225
       
-
       
  -iA</command>.</para></listitem>

     

       
0
       
 
       

     

       
226
       
 
       


     

       
227
       
 
       
  <listitem><para>The filename for (the directory containing) the Nix

     

       
228
       
 
       
  expression.</para></listitem>

     
···

       
259
       
 
       
  Also append <literal>"unstable"</literal> to the name - e.g.,

     

       
260
       
 
       
  <literal>"pkgname-unstable-2014-09-23"</literal>.</para></listitem>

     

       
261
       
 
       


     

       
262
       
-
       
  <listitem><para>Dashes in the package name should be preserved

     

       
263
       
-
       
  in new variable names, rather than converted to underscores

     

       
264
       
-
       
  (which was convention up to around 2013 and most names

     

       
265
       
-
       
   still have underscores instead of dashes) — e.g.,

     

       
266
       
-
       
  <varname>http-parser</varname> instead of

     

       
267
       
-
       
  <varname>http_parser</varname>.</para></listitem>

     

       
268
       
 
       


     

       
269
       
 
       
  <listitem><para>If there are multiple versions of a package, this

     

       
270
       
 
       
  should be reflected in the variable names in

     

···

       
18
       
 
       
  tab settings so it’s asking for trouble.</para></listitem>

     

       
19
       
 
       


     

       
20
       
 
       
  <listitem><para>Use <literal>lowerCamelCase</literal> for variable

     

       
21
       
+
       
  names, not <literal>UpperCamelCase</literal>.  Note, this rule does

     

       
22
       
+
       
  not apply to package attribute names, which instead follow the rules

     

       
23
       
+
       
  in <xref linkend="sec-package-naming"/>.</para></listitem>

     

       
24
       
 
       


     

       
25
       
 
       
  <listitem><para>Function calls with attribute set arguments are

     

       
26
       
 
       
  written as

     
···

       
220
       
 
       


     

       
221
       
 
       
  <listitem><para>The variable name used for the instantiated package

     

       
222
       
 
       
  in <filename>all-packages.nix</filename>, and when passing it as a

     

       
223
       
+
       
  dependency to other functions.  Typically this is called the

     

       
224
       
+
       
  <emphasis>package attribute name</emphasis>.  This is what Nix

     

       
225
       
+
       
  expression authors see.  It can also be used when installing using

     

       
226
       
+
       
  <command>nix-env -iA</command>.</para></listitem>

     

       
227
       
 
       


     

       
228
       
 
       
  <listitem><para>The filename for (the directory containing) the Nix

     

       
229
       
 
       
  expression.</para></listitem>

     
···

       
260
       
 
       
  Also append <literal>"unstable"</literal> to the name - e.g.,

     

       
261
       
 
       
  <literal>"pkgname-unstable-2014-09-23"</literal>.</para></listitem>

     

       
262
       
 
       


     

       
263
       
+
       
  <listitem><para>Dashes in the package name should be preserved in

     

       
264
       
+
       
  new variable names, rather than converted to underscores or camel

     

       
265
       
+
       
  cased — e.g., <varname>http-parser</varname> instead of

     

       
266
       
+
       
  <varname>http_parser</varname> or <varname>httpParser</varname>.  The

     

       
267
       
+
       
  hyphenated style is preferred in all three package

     

       
268
       
+
       
  names.</para></listitem>

     

       
269
       
 
       


     

       
270
       
 
       
  <listitem><para>If there are multiple versions of a package, this

     

       
271
       
 
       
  should be reflected in the variable names in

     

···

       
22
       
 
       
};

     

       
23
       
 
       
</programlisting>

     

       
24
       
 
       


     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
0
       
 
       

     

       
25
       
 
       
</para>

     

       
26
       
 
       


     

       
27
       
 
       
<para>The function <varname>mkOption</varname> accepts the following arguments.

     

···

       
22
       
 
       
};

     

       
23
       
 
       
</programlisting>

     

       
24
       
 
       


     

       
25
       
+
       
The attribute names within the <replaceable>name</replaceable>

     

       
26
       
+
       
attribute path must be camel cased in general but should, as an

     

       
27
       
+
       
exception, match the

     

       
28
       
+
       
<link

     

       
29
       
+
       
xlink:href="https://nixos.org/nixpkgs/manual/#sec-package-naming">

     

       
30
       
+
       
package attribute name</link> when referencing a Nixpkgs package. For

     

       
31
       
+
       
example, the option <varname>services.nix-serve.bindAddress</varname>

     

       
32
       
+
       
references the <varname>nix-serve</varname> Nixpkgs package.

     

       
33
       
+
       


     

       
34
       
 
       
</para>

     

       
35
       
 
       


     

       
36
       
 
       
<para>The function <varname>mkOption</varname> accepts the following arguments.