Argument Parsing

MILC exposes the full power of argparse to you. It also extends argparse to make certain commonly used patterns easier to use.

Reading Arguments

In most cases you will want to use cli.config to read your argument. For example:

cli.config.general.verbose

In some cases (such as arg_only) you will need to access the arguments directly using cli.args. You can access these using either attribute or dictionary notation:

Attribute:

cli.args.verbose

Dictionary:

cli.args['verbose']

Defining arguments

Argument Decorators

Argument decorators (@argument()) are used to define command line flags that the user has passed. For the most part the arguments passed to this decorator are passed to ArgumentParser.add_argument() directly. As such you can use all of those method arguments with MILC's @argument() decorator.

arg_only

Sometimes you want an argument to be a CLI flag only, and to not have a corresponding configuration option. With arg_only=True in your @argument() decorator this is possible. You will have to look in cli.args to find the value of that flag, it will not be populated to cli.config.

completers

You can specify argcomplete completers for your arguments by passing completers. For more detail see the argcomplete page.

deprecated

You can use the deprecated argument to mark a flag as deprecated. To use this you should set it to a string that will be displayed in --help. For example:

@argument('--old', action='store_true', deprecated='Use --new instead', help='The old action for my command.')

This will result in the following help output:

--old       The old action for my command. [Deprecated]: Use --new instead

action: store_boolean

In addition to the normal set of action= arguments that you can pass to @argument(), you can also pass a new action called store_boolean. This action behaves like store_true except that it adds a corresponding --no-<argument> flag that the user can pass as well.