numbers as varying radix values, 15 0xF 0o17 1111

[jtmoon79]

tl;dr a nice feature for numbers would allow reading passed argument as differing radix among the traditional hexadecimal, decimal, octal, and binary.

I have implemented this here. It's a good bit of work. Would be nice if clap handled this for me. I'm imagining an option like allow_radix_all

    #[clap(
        required = false,
        long,
        default_value_t = 0xFFFF,
        allow_radix_all,
    )]
    number: u64,

And perhaps, further fine-grained options would also be allowed: allow_radix_hexadecimal, allow_radix_octal, allow_radix_binary. So allow_radix_all would just enable all the prior.
And might even want to throw in disallow_radix_decimal for some users that really want such.

Parsing could require a prepended 0 before the radix symbol, e.g. 0xF, 0d15, 0o17, 0b1111 and reject without, e.g. xF, d15, o17, b1111. or could be flexible and accept both. I'm not sure what is best there.

[epage]

I went ahead and converted this over to an issue at #4564. This doesn't mean it will be done or that it will be done exactly as listed here but I would like higher visibility for any discussions on this.