mergeOptionDecls

lib.modules.mergeOptionDecls

Docs pulled from | This Revision | 21 minutes ago

Merge multiple option declarations into a single declaration. In general, there should be only one declaration of each option. The exception is the ‘options’ attribute, which specifies sub-options. These can be specified multiple times to allow one module to add sub-options to an option declared somewhere else (e.g. multiple modules define sub-options for ‘fileSystems’).

'loc' is the list of attribute names where the option is located.

'opts' is a list of modules. Each module has an options attribute which correspond to the definition of 'loc' in 'opt.file'.

Inputs

loc: 1. Function argument
opts: 2. Function argument

Noogle detected

Aliases

lib.mergeOptionDecls

Implementation

The following is the current implementation of this function.

mergeOptionDecls =
   loc: opts:
    foldl' (res: opt:
      let t  = res.type;
          t' = opt.options.type;
          mergedType = t.typeMerge t'.functor;
          typesMergeable = mergedType != null;
          typeSet = if (bothHave "type") && typesMergeable
                       then { type = mergedType; }
                       else {};
          bothHave = k: opt.options ? ${k} && res ? ${k};
      in
      if bothHave "default" ||
         bothHave "example" ||
         bothHave "description" ||
         bothHave "apply" ||
         (bothHave "type" && (! typesMergeable))
      then
        throw "The option `${showOption loc}' in `${opt._file}' is already declared in ${showFiles res.declarations}."
      else
        let
          getSubModules = opt.options.type.getSubModules or null;
          submodules =
            if getSubModules != null then map (setDefaultModuleLocation opt._file) getSubModules ++ res.options
            else res.options;
        in opt.options // res //
          { declarations = res.declarations ++ [opt._file];
            # In the case of modules that are generated dynamically, we won't
            # have exact declaration lines; fall back to just the file being
            # evaluated.
            declarationPositions = res.declarationPositions
              ++ (if opt.pos != null
                then [opt.pos]
                else [{ file = opt._file; line = null; column = null; }]);
            options = submodules;
          } // typeSet
    ) { inherit loc; declarations = []; declarationPositions = []; options = []; } opts;