f402fd73f2
for an option. * Removed double declaration for services.xserver.layout. svn path=/nixos/trunk/; revision=9398
34 lines
1 KiB
Nix
34 lines
1 KiB
Nix
# Given a configuration, this function returns an object with a `get'
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# method for retrieving the values of options, falling back to the
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# defaults declared in options.nix if no value is given for an
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# option.
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pkgs: config:
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let lib = pkgs.library; in
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rec {
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# The option declarations, i.e., option names with defaults and
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# documentation.
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declarations = import ./options.nix {inherit pkgs;};
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# Get the option named `name' from the user configuration, using
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# its default value if it's not defined.
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get = name:
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let
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decl =
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lib.findSingle (decl: lib.eqLists decl.name name)
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(abort ("Undeclared option `" + printName name + "'."))
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(abort ("Multiple declarations for option `" + printName name + "'."))
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declarations;
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default =
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if !decl ? default
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then abort ("Option `" + printName name + "' has no default.")
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else decl.default;
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in lib.getAttr name default config;
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printName = name: lib.concatStrings (lib.intersperse "." name);
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}
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