.default() method for the grid_*() functions

We have .default() methods for several other generics, but not for the grid functions. (The one for encode_unit() needs fixing: #430.)

library(dials)
#> Loading required package: scales

# no default method
grid_regular("foo")
#> Error in `UseMethod()`:
#> ! no applicable method for 'grid_regular' applied to an object of class "character"

# with default method
parameters("foo") 
#> Error in `parameters()`:
#> ! <parameters> objects cannot be created from a string.

finalize("foo")
#> Error in `finalize()`:
#> ! Cannot finalize a string.

encode_unit("foo")
#> Error in `encode_unit()`:
#> ! argument "direction" is missing, with no default

^{Created on 2026-02-23 with reprex v2.1.1}

Fix

We might change what happens if x is missing (see #428) but until then, we need to catch that case. Otherwise {.obj_type_friendly {x}} fails.

#' @export
#' @rdname grid_regular
grid_regular.default <- function(
  x,
  ...,
  levels = 3,
  original = TRUE,
  filter = NULL
) {
  if (missing(x)) {
    cli::cli_abort("At least one parameter object is required.")
  }
  cli::cli_abort(
    "{.arg x} must be a {.cls param} object, list, or {.cls parameters}, not
    {.obj_type_friendly {x}}."
  )
}

Add

  # wrong type
  expect_snapshot(error = TRUE, grid_random("not a param"))

to test_that("grid_random() errors with non-param inputs", {...})

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`.default()` method for the `grid_*()` functions #429

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.default() method for the grid_*() functions #429

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hfrick commented on Apr 7, 2026

Fix

hfrick commented on Apr 7, 2026

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`.default()` method for the `grid_*()` functions #429