Split extra help item computing with help record rendering

[kdeldycke]

I maintain Click Extra, a drop-in replacement for Click which adds colorization of the help screen.

I am currently relying on finicky regular expressions to identify and match the extra items that are displayed at the end of each option's help. These extra items are rendered in square brackets and looks like:

• [default: None]
• [default: (unlimited)]
• [env var: COLOR_CLI8_TIME; default: no-time]
• and a variety of other formats.

The problem is that the generation of these extra items are deeply embedded within Click and are impossible to fetch independently.

That's why I propose a simple refactor of the Option.get_help_record() method, and split it in two:

• a new method to compute the values of these extra items
• keep the original get_help_record() as-is, but dedicated to help message rendering only

I have a PR that is ready at #2517.

[kdeldycke]

Just wanted to ping @janluke on that issue, as he also maintain a Click-based extension that is also deep into help screen customization and coloring.

[kdeldycke]

I've also heard rumors of upcoming big refactors regarding help screen generation, so I propose this small, un intrusive one as a small step towards the big one.