nixpkgs/lib/cli.nix
Gabriel Gonzalez 183a99734f Add pkgs.lib.renderOptions
This adds a new utility to intelligently convert Nix records to
command line options to reduce boilerplate for simple use cases and to
also reduce the likelihood of malformed command lines
2019-12-11 16:30:05 -08:00

34 lines
1 KiB
Nix

{ lib }:
{ /* Automatically convert an attribute set to command-line options.
This helps protect against malformed command lines and also to reduce
boilerplate related to command-line construction for simple use cases.
Example:
renderOptions { foo = "A"; bar = 1; baz = null; qux = true; v = true; }
=> " --bar '1' --foo 'A' --qux -v"
*/
renderOptions =
options:
let
render = key: value:
let
hyphenate =
k: if builtins.stringLength k == 1 then "-${k}" else "--${k}";
renderOption = v: if v == null then "" else " ${hyphenate key} ${lib.escapeShellArg v}";
renderSwitch = if value then " ${hyphenate key}" else "";
in
if builtins.isBool value
then renderSwitch
else if builtins.isList value
then lib.concatMapStrings renderOption value
else renderOption value;
in
lib.concatStrings (lib.mapAttrsToList render options);
}