Is there any a way to make ./app --help the default behavior when there's no argument passed?

[ghost]

Hi 😃 ! Thanks for making/maintaining this library.

I've been looking for this in the doc, but sadly I couldn't find it or missed it somewhere (most likely).

I wonder if we could invoke the program without arguments and let it show us the help message by default, the same if you pass --help to the program. For reference, please see Haskell's optparse-applicative package with showHelpOnEmpty preference enabled.

This is what I have in mind:

    // top-level options parser
    construct!([tui_cmd, install_cmd])
        .to_options()
        .show_help_on_empty()
        .version("v0.1.0")
        .run()

Output example:

$ ./app
Usage: COMMAND ...

Available options:
    -h, --help     Prints help information
    -V, --version  Prints version information

Available commands:
    tui      Show TUI interface
    install  Install

Thanks!

[pacak]

Thanks for making/maintaining this library.

Thank you for the kind words :)

I wonder if we could invoke the program without arguments and let it show us the help message by default, the same if you pass --help to the program.

Not in the current version, but it might change in the future given enough demand. For now you can do something like this to achieve the same results:

#186

[ghost]

Thank you!

[pacak]

Since 0.9.1 you can use OptionParser::fallback_to_usage, see https://github.com/pacak/bpaf/blob/bc42de419b15aba586bd4cd2f0b7874f3f915d38/examples/basic.rs