Allows extension packages to make use of the formula parsing of specials.
new_specials(..., .required_specials = NULL, .xreg_specials = NULL)
| ... | A named set of functions which used to parse formula inputs |
|---|---|
| .required_specials | The names of specials which must be provided (and if not, are included with no inputs). |
| .xreg_specials | The names of specials which will be only used as inputs to other specials (most commonly |