Boolean options¶

If you specify an option for --dev:

- !Option [dev, !Type bool]

the .dev attribute will be None if that options is not specified and True if it is specified, so you should be able to just use it with if args.dev:

If you explicitly want the attribute to be False if the option is not specified use:

- !Option [dev, !Type bool, !Default False]

storing False¶

You can create an "inverse" boolean option, that defaults to True if not specified and to False if it is using:

- !Option [dev, !Type bool, !Const False, !Default True]

tri-state with --no-¶

If you want both an option --dev and an option --no-dev, the later e.g. to be able to reverse the default value read from a configuration file, you need to specify two options that write to the same destination attribute:

- !Option [dev, !Type bool]   # without !Dest uses the first (long) option as destination
- !Option [no-dev, !Type bool, !Dest dev, !Const False]

This is actually a tri-state, with None as attribute value when neither --dev nor --no-dev were specified.