···

       
261
       
261
       
 
       
  evalOptionValue = loc: opt: defs:

     

       
262
       
262
       
 
       
    let

     

       
263
       
263
       
 
       
      # Add in the default value for this option, if any.

     

       
264
       
264
       
-
       
      defs' = (optional (opt ? default)

     

       
265
       
265
       
-
       
        { file = head opt.declarations; value = mkOptionDefault opt.default; }) ++ defs;

     

       
264
       
264
       
+
       
      defs' =

     

       
265
       
265
       
+
       
          (optional (opt ? default)

     

       
266
       
266
       
+
       
            { file = head opt.declarations; value = mkOptionDefault opt.default; }) ++ defs;

     

       
266
       
267
       
 
       


     

       
267
       
268
       
 
       
      # Handle properties, check types, and merge everything together.

     

       
268
       
268
       
-
       
      res = mergeDefinitions loc opt.type defs';

     

       
269
       
269
       
+
       
      res =

     

       
270
       
270
       
+
       
        if opt.readOnly or false && length defs' > 1 then

     

       
271
       
271
       
+
       
          throw "The option `${showOption loc}' is read-only, but it's set multiple times."

     

       
272
       
272
       
+
       
        else

     

       
273
       
273
       
+
       
          mergeDefinitions loc opt.type defs';

     

       
269
       
274
       
 
       


     

       
270
       
275
       
 
       
      # Check whether the option is defined, and apply the ‘apply’

     

       
271
       
276
       
 
       
      # function to the merged value.  This allows options to yield a

     

···

       
19
       
19
       
 
       
    , apply ? null # Function that converts the option value to something else.

     

       
20
       
20
       
 
       
    , internal ? null # Whether the option is for NixOS developers only.

     

       
21
       
21
       
 
       
    , visible ? null # Whether the option shows up in the manual.

     

       
22
       
22
       
+
       
    , readOnly ? null # Whether the option can be set only once

     

       
22
       
23
       
 
       
    , options ? null # Obsolete, used by types.optionSet.

     

       
23
       
24
       
 
       
    } @ attrs:

     

       
24
       
25
       
 
       
    attrs // { _type = "option"; };

     
···

       
90
       
91
       
 
       
          declarations = filter (x: x != unknownModule) opt.declarations;

     

       
91
       
92
       
 
       
          internal = opt.internal or false;

     

       
92
       
93
       
 
       
          visible = opt.visible or true;

     

       
94
       
94
       
+
       
          readOnly = opt.readOnly or false;

     

       
93
       
95
       
 
       
          type = opt.type.name or null;

     

       
94
       
96
       
 
       
        }

     

       
95
       
97
       
 
       
        // (if opt ? example then { example = scrubOptionValue opt.example; } else {})

     

···

       
39
       
39
       
 
       
                  <emphasis>Type:</emphasis>

     

       
40
       
40
       
 
       
                  <xsl:text> </xsl:text>

     

       
41
       
41
       
 
       
                  <xsl:apply-templates select="attr[@name = 'type']" mode="top" />

     

       
42
       
42
       
+
       
                  <xsl:if test="attr[@name = 'readOnly']/bool/@value = 'true'">

     

       
43
       
43
       
+
       
                    <xsl:text> </xsl:text>

     

       
44
       
44
       
+
       
                    <emphasis>(read only)</emphasis>

     

       
45
       
45
       
+
       
                  </xsl:if>

     

       
42
       
46
       
 
       
                </para>

     

       
43
       
47
       
 
       
              </xsl:if>

     

       
44
       
48
       
 
       


     

···

       
29
       
29
       
 
       
    };

     

       
30
       
30
       
 
       


     

       
31
       
31
       
 
       
    system.nixosRelease = mkOption {

     

       
32
       
32
       
-
       
      internal = true;

     

       
32
       
32
       
+
       
      readOnly = true;

     

       
33
       
33
       
 
       
      type = types.str;

     

       
34
       
34
       
 
       
      default = readFile "${toString pkgs.path}/.version";

     

       
35
       
35
       
 
       
      description = "NixOS release.";

     
···

       
48
       
48
       
 
       
    };

     

       
49
       
49
       
 
       


     

       
50
       
50
       
 
       
    system.nixosCodeName = mkOption {

     

       
51
       
51
       
-
       
      internal = true;

     

       
51
       
51
       
+
       
      readOnly = true;

     

       
52
       
52
       
 
       
      type = types.str;

     

       
53
       
53
       
 
       
      description = "NixOS release code name.";

     

       
54
       
54
       
 
       
    };