Re: palette registry/lookup

[teunbrand]

These are just some notes from the meeting we had off-github, so I can safely forget them in a while.

• We should give some thoughts about 'namespacing' palette names. E.g. do we recommend packages prefix their names before palettes, so that the {foobar} package defines a "foobar::pal_xyz" palette?
• If we go with namespaced palette names, do we automatically look these up from packages that aren't loaded?
• Should we do away with the current registration mechanism and ensure that we lookup "foobar::pal_xyz" regardless of whether that function was registered as a palette?
  • My reservation here is that we don't know if that palette is discrete or continuous and how to convert between them.
• Do we make a small guide about our recommendations for palette packages?
  • Consider making a testthat expectation that people can use.

Inspiration: https://github.com/EmilHvitfeldt/paletteer?tab=readme-ov-file#examples

[teunbrand]

Should we do away with the current registration mechanism and ensure that we lookup "foobar::pal_xyz" regardless of whether that function was registered as a palette?

If we recommend packages export a colour vector, we can simply use as_continuous_pal(pkgname::col_vec) instead of as_continuous_pal('pkgname::col_vec'). In this case, there is no need to register a palette.

The set_palette() function is still convenient if you have a palette function instead of a colour vector. This is convenient if palettes construct their colours mathematically instead of interpolate between known colours (like pal_hue() does for example).