Minor Enhancement Ideas

[phlptp]

In the course of integration into our applications, A couple ideas came up that would make things a little easier. There are clear workarounds so isn't critical by any means.

1. Having the footer be optionally a callback. There were a few situations where the command line gets parsed in multiple stages. Needing to create an object from the arguments in the first pass for example. And in the help we currently intercept the helpError and then print the normal help then do a few things to generate a second portion of the help. It would simplify things if the footer could be a callback that could trigger a few of things automatically.

2. Having positional arguments only match on validation. For example we might have positional arguments, one being a file and one being a number. Right now these match in order of definition, but this can get a little complicated in the presence of option groups. It would relax the requirements and care needed if positionals were only able to match if they validate. That would also make the command line entry be a little more flexible concerning positionals as well. Right now reversing the order would result in an error, while if they matched on validation, either order would be fine.

Just a few ideas that are coming out of our integration with CLI11. So far the results have been quite positive!

[phlptp]

This was closed by #262 and #309