Support core::fmt::Display and alternative formats.

[reitermarkus]

No description provided.

[svartalf]

Hey, @reitermarkus! Thanks for a pull request :)

Can we start with the master rebasing? Apparently, I broke the CI in here and it is fixed now in 16784c4

[svartalf]

I checked the docs about the MAC addresses and have a proposal to change the formatting a bit.

There are three possible ways to display the address:

1. hypen notation (00-00-00-00-00-00)
2. colon notation (00:00:00:00:00:00)
3. period-separated notation (000.000.000.000)

We can make the colon notation to be the default formatting option, use Formatter::sign_minus to display the hypen notation and Formatter::alternate to display the period-separated notation; that way we could cover all three notations at once.

I'm not sure about your default formatting 000000000000, though, is it used anywhere in a wild?

[reitermarkus]

I'm not sure about your default formatting 000000000000, though, is it used anywhere in a wild?

I haven't seen it. I just thought having no separators by default and having to choose colons/hyphens explicitly would make sense.

[reitermarkus]

I left the other formats as is and added {:.0} for the period-separated notation.

[svartalf]

Dot format is used for a numeric types and afaik can't be used without supplying the precision, so it is impossible to use it as a {:.}, arbitrary precision should be supplied always, as in {:.0}.

This does not seems to be very convinient and easy to remember; had you thought on my idea about formatting options? I would love to hear your thoughts on that.

[reitermarkus]

I changed it now to your suggestion.

[svartalf]

That looks great! There is a small thing I would like to clarify, after that I'll be glad to merge and publish this PR :)

[svartalf]

Awesome, everything looks great! I'm going to change some things in CI, check the results and will try to publish your change today