Named, or alternative word-patterns

[ozra]

When searching word under cursor I prefer x_y_z to be matched as one, but when stepping with ctrl+r/l cursor-word-... I prefer to stop at _ boundaries.

It would be nice to be able to handle this in a smooth fashion, by for instance passing a word-pattern name/label/id and if not fallback to "default" / "primary" word-pattern.