tidyselect can't be used to provide column names

R/slide.R

@@ -557,7 +557,8 @@ epi_slide_opt <- function(x, col_names, f, ..., before, after, ref_time_values,
   window_size <- before + after + 1L
 
   pos <- eval_select(rlang::enquo(col_names), data = x)
-  result_col_names <- names(pos)
+  # Always rename results to "slide_value_<original column name>".
+  result_col_names <- paste0("slide_value_", names(x[, pos]))
   slide_one_grp <- function(.data_group, .group_key, ...) {
     missing_times <- all_dates[!(all_dates %in% .data_group$time_value)]
 
@@ -605,8 +606,7 @@ epi_slide_opt <- function(x, col_names, f, ..., before, after, ref_time_values,
 
     if (f_from_package == "data.table") {
       roll_output <- f(
-        x = rlang::set_names(.data_group[, pos], result_col_names),
-        n = window_size, align = "right", ...
+        x = .data_group[, pos], n = window_size, align = "right", ...
       )
 
       if (after >= 1) {
@@ -616,6 +616,8 @@ epi_slide_opt <- function(x, col_names, f, ..., before, after, ref_time_values,
         .data_group[, result_col_names] <- purrr::map(roll_output, function(.x) {
           c(.x[(after + 1L):length(.x)], rep(NA, after))
         })
+      } else {
+        .data_group[, result_col_names] <- roll_output
       }
     } else if (f_from_package == "slider") {
       for (i in seq_along(pos)) {

man-roxygen/opt-slide-params.R

@@ -1,5 +1,9 @@
-#' @param col_names A single tidyselection or a tidyselection vector of the
-#'  names of one or more columns for which to calculate the rolling mean.
+#' @param col_names A <[`tidy-select`][dplyr_tidy_select]> of the names of one
+#'  or more columns for which to calculate a rolling computation. One or more
+#'  unquoted expressions separated by commas. Variable names can be used as
+#'  if they were positions in the data frame, so expressions like `x:y` can
+#'  be used to select a range of variables. The tidyselection cannot be used
+#'  to provide output column names.
 #' @param as_list_col Not supported. Included to match `epi_slide` interface.
 #' @param new_col_name Character vector indicating the name(s) of the new
 #'  column(s) that will contain the derivative values. Default