Mutually exclusive option groups in python Click

I ran into this same use case recently; this is what I came up with. For each option, you can give a list of conflicting options.

from click import command, option, Option, UsageErrorclass MutuallyExclusiveOption(Option):    def __init__(self, *args, **kwargs):        self.mutually_exclusive = set(kwargs.pop('mutually_exclusive', []))        help = kwargs.get('help', '')        if self.mutually_exclusive:            ex_str = ', '.join(self.mutually_exclusive)            kwargs['help'] = help + (                ' NOTE: This argument is mutually exclusive with '                ' arguments: [' + ex_str + '].'            )        super(MutuallyExclusiveOption, self).__init__(*args, **kwargs)    def handle_parse_result(self, ctx, opts, args):        if self.mutually_exclusive.intersection(opts) and self.name in opts:            raise UsageError(                "Illegal usage: `{}` is mutually exclusive with "                "arguments `{}`.".format(                    self.name,                    ', '.join(self.mutually_exclusive)                )            )        return super(MutuallyExclusiveOption, self).handle_parse_result(            ctx,            opts,            args        )

Then use the regular option decorator but pass the cls argument:

@command(help="Run the command.")@option('--jar-file', cls=MutuallyExclusiveOption,        help="The jar file the topology lives in.",        mutually_exclusive=["other_arg"])@option('--other-arg',        cls=MutuallyExclusiveOption,        help="The jar file the topology lives in.",        mutually_exclusive=["jar_file"])def cli(jar_file, other_arg):    print "Running cli."    print "jar-file: {}".format(jar_file)    print "other-arg: {}".format(other_arg)if __name__ == '__main__':    cli() 

Here's a gist that includes the code above and shows the output from running it.

If that won't work for you, there's also a few (closed) issues mentioning this on the click github page with a couple of ideas that you may be able to use.

• https://github.com/pallets/click/issues/257
• https://github.com/pallets/click/issues/509

You could use the following package:https://github.com/espdev/click-option-group

import clickfrom click_option_group import optgroup, RequiredMutuallyExclusiveOptionGroup@click.command()@optgroup.group('Grouped options', cls=RequiredMutuallyExclusiveOptionGroup,                help='Group description')@optgroup.option('--all', 'all_', is_flag=True, default=False)@optgroup.option('--color')def cli(all_, color):    print(all_, color)if __name__ == '__main__':    cli()

app help:

$ app.py --helpUsage: app.py [OPTIONS]Options:  Grouped options: [mutually_exclusive, required]                                  Group description    --all    --color TEXT  --help                          Show this message and exit.

You could use Cloup, a package that adds option groups and constraints to Click. You have two options to solve this problem in Cloup.

Disclaimer: I'm the author of the package.

Option 1: @option_group

When you define an option group using @option_group, the options in each group are shown in separate help sections (like in argparse). You can apply constraints (like mutually_exclusive) to option groups as follows:

from cloup import command, option, option_groupfrom cloup.constraints import mutually_exclusive@command()@option_group(    'Color options',    option('--all', 'all_colors', is_flag=True),    option('--color'),    constraint=mutually_exclusive)def cmd(**kwargs):    print(kwargs)

The help will be:

Usage: cmd [OPTIONS]Color options [mutually exclusive]:  --all         --color TEXTOther options:  --help        Show this message and exit.

Option 2: @constraint

If you don't want option groups to show up in the command help, you can use @constraint and specify the constrained options by their (destination) name:

from cloup import command, optionfrom cloup.constraints import constraint, mutually_exclusive@command()@option('--all', 'all_colors', is_flag=True)@option('--color')@constraint(mutually_exclusive, ['all_colors', 'color'])def cmd(**kwargs):    print(kwargs)

Constraints defined this way can be documented in command help! This feature is disabled by default but can be easily enabled passing show_constraints=True to @command. The result:

Usage: cmd [OPTIONS]Options:  --all         --color TEXT  --help        Show this message and exit.Constraints:  {--all, --color}  mutually exclusive

The error message

In both case, if you run cmd --all --color red, you get:

Usage: cmd [OPTIONS]Try 'cmd --help' for help.Error: the following parameters are mutually exclusive:  --all   --color

Other constraints

Cloup defines constraints that should cover 99.9% of your needs. It even supports conditional constraints!

For example, if the user must provide one of your mutually exclusive options, replace mutually_exclusive with RequireExactly(1) in the example above.

You can find all available constraints here.