29 lines
953 B
Nix
29 lines
953 B
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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lib: config:
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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;
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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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sameName = lib.filter (opt: lib.eqLists opt.name name) declarations;
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default =
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if sameName == []
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then abort ("Undeclared option `" + printName name + "'.")
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else if !builtins.head sameName ? default
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then abort ("Option `" + printName name + "' has no default.")
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else (builtins.head sameName).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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