use option and warning if package is not installed

NAMESPACE

@@ -31,6 +31,7 @@ importFrom(purrr,pmap)
 importFrom(purrr,pwalk)
 importFrom(purrr,reduce)
 importFrom(purrr,when)
+importFrom(rlang,is_installed)
 importFrom(rlang,seq2)
 importFrom(utils,tail)
 importFrom(utils,write.table)

R/vertical.R

@@ -16,12 +16,20 @@ construct_vertical <- function(x) {
 #' @param colored Whether or not the output should be colored with
 #'   `prettycode::highlight()`.
 #' @param style Passed to `prettycode::highlight()`.
+#' @importFrom rlang is_installed
 #' @export
 print.vertical <- function(x, ...,
-                           colored = TRUE,
+                           colored = getOption("styler.colored_print.vertical"),
                            style = prettycode::default_style()) {
   if (colored) {
-    x <- prettycode::highlight(x, style = style)
+    if (is_installed("prettycode")) {
+      x <- prettycode::highlight(x, style = style)
+    } else {
+      warn(c(
+        "Could not use colored = TRUE, as the package prettycode is not",
+        "installed. Please install it if you want to see colored output."
+      ))
+    }
   }
   cat(x, sep = "\n")
 }

R/zzz.R

@@ -1,3 +1,11 @@
 .onLoad <- function(libname, pkgname) {
   backports::import(pkgname, "trimws")
+    op <- options()
+    op.styler <- list(
+      styler.colored_print.vertical = TRUE
+    )
+    toset <- !(names(op.styler) %in% names(op))
+    if(any(toset)) options(op.styler[toset])
+    invisible()
 }
+