R/01_package.R

In GegznaV/RcmdrPlugin.BioStat: R Commander Plug-in for Basic Data Management and Analysis Tasks

#' @name RcmdrPlugin.biostat
#' @docType package
#'
#' @title R Commander Plug-in for Basic Data Management and Analysis Tasks
#'
#' @description
#' \pkg{RcmdrPlugin.biostat} is an
#' \href{\pkg{Rcmdr}}{https://CRAN.R-project.org/package=Rcmdr}
#' plug-in for the most common data wrangling, visualisation and analysis tasks
#' using "tidyverse" family functions as well as functions from other packages.
#'
#' @rawNamespace import(tcltk, except = c(tkfocus, tclvalue, ttkentry))
#' @import tcltk2
#' @import Rcmdr
#' @import stringr
#' @import purrr
#' @import nortest
#' @import ggplot2
#' @importFrom dplyr glimpse is_grouped_df
#' @importFrom magrittr "%>%"  "%<>%"  "%T>%"  "%$%"
#' @importFrom graphics plot par
#' @importFrom stats p.adjust.methods C setNames
#' @importFrom utils browseURL packageVersion data installed.packages modifyList
#'                   capture.output tail vignette help globalVariables
#' @importFrom grDevices devAskNewPage dev.list dev.off
#' @importFrom stats na.omit

# @importFrom graphics text
# FIXME: check "text": importFrom("graphics", "text")
NULL

# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Variables
biostat_env <- new.env()
biostat_env$use_relative_path <- TRUE
# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

# Functions
.onLoad <- function(libname, pkgname) {
  if (!interactive()) {
    return()
  }

  # Options ------------------------------------------------------------------
  # set_default_bs_options()

  # Tcl/Tk path --------------------------------------------------------------
  # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  libdir <- file.path(libname, pkgname, "tklibs")
  add_tcl_path(libdir)

  # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  # Create icons -------------------------------------------------------------

  bs_tkimage_create("::image::dot-black",     "icons/oth/dot-black.png")
  bs_tkimage_create("::image::dot-red",       "icons/oth/dot-red.png")
  bs_tkimage_create("::image::dot-blue",      "icons/oth/dot-blue.png")
  bs_tkimage_create("::image::dot-lblue",     "icons/oth/dot-lblue.png")
  bs_tkimage_create("::image::dot-green",     "icons/oth/dot-green.png")
  bs_tkimage_create("::image::dot-lgreen",    "icons/oth/dot-lgreen.png")
  bs_tkimage_create("::image::dot-yellow",    "icons/oth/dot-yellow.png")
  bs_tkimage_create("::image::dot-grey",      "icons/oth/dot-grey.png")
  bs_tkimage_create("::image::dot-violet",    "icons/oth/dot-violet.png")

  bs_tkimage_create("::image::dot-gw-4",      "icons/oth/dot-gw-4x4.png")
  # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  bs_tkimage_create("::image::bs_r_logo_analysis",      "icons/32/bs-analysis-32.png")
  bs_tkimage_create("::image::bs_r_logo_documentation", "icons/32/documentation.png")
  bs_tkimage_create("::image::bs_r_logo_help",          "icons/32/system-help-2.png")
  bs_tkimage_create("::image::bs_r_logo_internet",      "icons/32/applications-internet.png")
  bs_tkimage_create("::image::bs_r_logo_management",    "icons/32/management.png")
  bs_tkimage_create("::image::bs_r_logo_plots",         "icons/32/office-chart-pie.png")
  bs_tkimage_create("::image::bs_r_logo_settings",      "icons/32/system-settings.png")
  bs_tkimage_create("::image::bs_r_logo_shapes",        "icons/32/shapes.png")
  # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  bs_tkimage_create("::image::bs_r_logo_b",  "icons/32/R-logo-b.png")
  bs_tkimage_create("::image::bs_r_logo_br", "icons/32/R-logo-br.png")
  bs_tkimage_create("::image::bs_r_logo_bw", "icons/32/R-logo-bw.png")
  bs_tkimage_create("::image::bs_r_logo_lb", "icons/32/R-logo-lb.png")
  bs_tkimage_create("::image::bs_r_logo_c",  "icons/32/R-logo-c.png")
  bs_tkimage_create("::image::bs_r_logo_g",  "icons/32/R-logo-g.png")
  bs_tkimage_create("::image::bs_r_logo_lg", "icons/32/R-logo-lg.png")
  bs_tkimage_create("::image::bs_r_logo_r",  "icons/32/R-logo-r.png")
  bs_tkimage_create("::image::bs_r_logo_v",  "icons/32/R-logo-v.png")
  bs_tkimage_create("::image::bs_r_logo_y",  "icons/32/R-logo-y.png")
  # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  bs_tkimage_create("::image::bs_r",        "icons/16/r-logo-16x16.png")
  bs_tkimage_create("::image::bs_r_blue",   "icons/16/r-logo-b-16x16.png")
  bs_tkimage_create("::image::bs_r_brown",  "icons/16/r-logo-br-16x16.png")
  bs_tkimage_create("::image::bs_r_bw",     "icons/16/r-logo-bw-16x16.png")
  bs_tkimage_create("::image::bs_r_lblue",  "icons/16/r-logo-lb-16x16.png")
  bs_tkimage_create("::image::bs_r_cyan",   "icons/16/r-logo-c-16x16.png")
  bs_tkimage_create("::image::bs_r_green",  "icons/16/r-logo-g-16x16.png")
  bs_tkimage_create("::image::bs_r_lgreen", "icons/16/r-logo-lg-16x16.png")
  bs_tkimage_create("::image::bs_r_red",    "icons/16/r-logo-r-16x16.png")
  bs_tkimage_create("::image::bs_r_violet", "icons/16/r-logo-v-16x16.png")
  bs_tkimage_create("::image::bs_r_yellow", "icons/16/r-logo-y-16x16.png")

  bs_tkimage_create("::image::bs_dataset", "icons/16/list.png")
  bs_tkimage_create("::image::bs_model",   "icons/16/model.png")

  bs_tkimage_create("::image::bs_ok",         "icons/16/dialog-ok-apply-5.png")
  bs_tkimage_create("::image::bs_tick",       "icons/16/dialog-ok-apply-5.png")
  bs_tkimage_create("::image::bs_delete",     "icons/16/delete.png")
  bs_tkimage_create("::image::bs_paste",      "icons/16/edit-paste-7.png")
  bs_tkimage_create("::image::bs_copy",       "icons/16/edit-copy-7.png")
  bs_tkimage_create("::image::bs_rename",     "icons/16/textfield-rename.png")
  bs_tkimage_create("::image::bs_cut",        "icons/16/edit-cut-7.png")
  bs_tkimage_create("::image::bs_undo",       "icons/16/edit-undo-7.png")
  bs_tkimage_create("::image::bs_redo",       "icons/16/edit-redo-7.png")
  bs_tkimage_create("::image::bs_find",       "icons/16/edit-find-7.png")
  bs_tkimage_create("::image::bs_refresh",    "icons/16/refresh.png")
  bs_tkimage_create("::image::bs_reset",      "icons/16/refresh-r.png")
  bs_tkimage_create("::image::bs_select_all", "icons/16/edit-select-all.png")
  bs_tkimage_create("::image::bs_down",       "icons/16/down-blue.png")
  bs_tkimage_create("::image::bs_chk_pkgs",   "icons/16/view-refresh-6.png")

  bs_tkimage_create("::image::bs_choose_file", "icons/16/document-open.png")
  bs_tkimage_create("::image::bs_open_file",   "icons/16/document-open-file.png")
  bs_tkimage_create("::image::bs_open_dir",    "icons/16/document-open-folder.png")
  bs_tkimage_create("::image::bs_table",       "icons/16/kdb_table.png")
  bs_tkimage_create("::image::bs_rectangle",   "icons/16/draw-rectangle.png")

  bs_tkimage_create("::image::bs_go_top",     "icons/16/go-top-3.png")
  bs_tkimage_create("::image::bs_go_up",      "icons/16/go-up-4.png")
  bs_tkimage_create("::image::bs_go_down",    "icons/16/go-down-4.png")
  bs_tkimage_create("::image::bs_go_bottom",  "icons/16/go-bottom-3.png")

  bs_tkimage_create("::image::bs_go_first",   "icons/16/go-first-2.png")
  bs_tkimage_create("::image::bs_go_prev",    "icons/16/go-previous-4.png")
  bs_tkimage_create("::image::bs_go_next",    "icons/16/go-next-4.png")
  bs_tkimage_create("::image::bs_go_last",    "icons/16/go-last-2.png")

  bs_tkimage_create("::image::bs_sort_asc",   "icons/16/sort_ascending.png")
  bs_tkimage_create("::image::bs_sort_desc",  "icons/16/sort_descending.png")
  # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  bs_tkimage_create("::image::bs_import",     "icons/16/bs_import.png")
  bs_tkimage_create("::image::bs_text",       "icons/16/bs_txt.png")
  bs_tkimage_create("::image::bs_excel",      "icons/16/page-white_excel.png")
  bs_tkimage_create("::image::bs_geogebra",   "icons/16/geogebra.png")
  bs_tkimage_create("::image::bs_package",    "icons/16/package-green.png")
  bs_tkimage_create("::image::bs_package_r",  "icons/16/package-red.png")
  bs_tkimage_create("::image::bs_package_br", "icons/16/package-br.png")
  bs_tkimage_create("::image::bs_package_go", "icons/16/package-go.png")
  bs_tkimage_create("::image::bs_wpd",        "icons/16/wpd-16x16.png")
  bs_tkimage_create("::image::bs_new_doc",    "icons/16/document-new-3.png")

  bs_tkimage_create("::image::bs_word",       "icons/16/page-white_word.png")
  bs_tkimage_create("::image::bs_pptx",       "icons/16/page-white_powerpoint.png")
  # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  bs_tkimage_create("::image::bs_export",     "icons/16/bs_export.png")
  bs_tkimage_create("::image::bs_md",         "icons/16/md.png")
  bs_tkimage_create("::image::bs_print_as_df", "icons/16/bs-print-as-df.png")
  # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  bs_tkimage_create("::image::bs_objects",    "icons/16/emblem-documents.png")
  bs_tkimage_create("::image::bs_join",       "icons/16/application-side-list.png")
  bs_tkimage_create("::image::bs_bind_rows",  "icons/16/application-tile-vertical.png")
  bs_tkimage_create("::image::bs_bind_cols",  "icons/16/application-tile-horizontal.png")
  # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  bs_tkimage_create("::image::bs_rows",                "icons/16/bs_rows.png")
  bs_tkimage_create("::image::bs_rows_sort",           "icons/16/bs_rows_sort.png")
  bs_tkimage_create("::image::bs_rows_names",          "icons/16/bs_rows_names.png")
  bs_tkimage_create("::image::bs_rows_have_names",     "icons/16/bs_rows_have_names.png")
  bs_tkimage_create("::image::bs_rows_names_print",    "icons/16/bs_rows_names_print.png")
  bs_tkimage_create("::image::bs_rows_names_to_col",   "icons/16/bs_rows_names_to_col.png")
  bs_tkimage_create("::image::bs_rows_names_to_names", "icons/16/bs_rows_names_to_names.png")
  bs_tkimage_create("::image::bs_rows_number",         "icons/16/bs_rows_number.png")
  bs_tkimage_create("::image::bs_rows_select",         "icons/16/bs_rows_select.png")
  bs_tkimage_create("::image::bs_rows_filter",         "icons/16/bs_rows_filter.png")
  bs_tkimage_create("::image::bs_rows_slice",          "icons/16/bs_rows_slice.png")
  bs_tkimage_create("::image::bs_rows_top_bot",        "icons/16/bs_rows_top_bottom.png")
  bs_tkimage_create("::image::bs_rows_duplicates",     "icons/16/bs_rows_duplicates.png")
  # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  bs_tkimage_create("::image::bs_columns",           "icons/16/bs_cols.png")
  bs_tkimage_create("::image::bs_cols_names",        "icons/16/bs_cols_names.png")
  bs_tkimage_create("::image::bs_cols_names_print",  "icons/16/bs_cols_names_print.png")
  bs_tkimage_create("::image::bs_cols_names_check",  "icons/16/bs_cols_names_check.png")
  bs_tkimage_create("::image::bs_cols_names_clean",  "icons/16/bs_cols_names_clean.png")
  bs_tkimage_create("::image::bs_cols_names_rename", "icons/16/bs_cols_names_rename.png")
  bs_tkimage_create("::image::bs_cols_select",       "icons/16/bs_cols_select.png")
  bs_tkimage_create("::image::bs_cols_compute",      "icons/16/bs_cols_compute.png")
  bs_tkimage_create("::image::bs_cols_mutate",       "icons/16/bs_cols_mutate.png")
  bs_tkimage_create("::image::bs_cols_recode",       "icons/16/bs_cols_recode.png")
  bs_tkimage_create("::image::bs_cols_convert",      "icons/16/bs_cols_convert.png")
  bs_tkimage_create("::image::bs_data_reshape",      "icons/16/bs_data_reshape.png")
  bs_tkimage_create("::image::bs_data_chr",          "icons/16/bs_data_chr.png")
  bs_tkimage_create("::image::bs_data_fct",          "icons/16/bs_data_fct.png")
  bs_tkimage_create("::image::bs_data_num",          "icons/16/bs_data_num.png")
  # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  bs_tkimage_create("::image::bs_preview",    "icons/16/document-preview.png")
  bs_tkimage_create("::image::bs_glimpse",    "icons/16/glimpse_16.png")
  bs_tkimage_create("::image::bs_na_red",     "icons/16/bs_na_red.png")
  bs_tkimage_create("::image::bs_na_blue",    "icons/16/bs_na_blue.png")
  # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  bs_tkimage_create("::image::bs_summary",    "icons/16/bs_enumlist.png")
  bs_tkimage_create("::image::bs_desc",       "icons/16/bs_desc.png")
  # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  bs_tkimage_create("::image::bs_analyze",    "icons/16/bs_analyze.png")
  bs_tkimage_create("::image::bs_normality",  "icons/16/bs_normality.png")
  # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  bs_tkimage_create("::image::bs_plot",       "icons/16/office-chart-pie.png")
  bs_tkimage_create("::image::bs_new_window", "icons/16/window-new.png")
  bs_tkimage_create("::image::bs_plot_close", "icons/16/delete.png")
  bs_tkimage_create("::image::bs_plotly",     "icons/16/plotly.png")
  bs_tkimage_create("::image::bs_chart",      "icons/16/insert-chart-bar.png")
  bs_tkimage_create("::image::bs_ggplot",     "icons/16/insert-chart-bar.png")
  # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  # bs_tkimage_create("::image::bs_web",        "icons/16/applications-internet.png")
  bs_tkimage_create("::image::bs_web",        "icons/16/emblem-web.png")
  bs_tkimage_create("::image::bs_web_get",    "icons/16/application-x-kgetlist.png")
  bs_tkimage_create("::image::bs_web_app",    "icons/16/application-x-desktop.png")

  # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  bs_tkimage_create("::image::bs_settings",    "icons/16/system-2.png")
  bs_tkimage_create("::image::bs_locale",      "icons/16/locale.png")

  bs_tkimage_create("::image::bs_load_pkg",    "icons/16/edit-redo-7.png")
  bs_tkimage_create("::image::bs_load_pkg_c",  "icons/16/edit-redo-7-c.png")

  bs_tkimage_create("::image::bs_restart",     "icons/16/refresh-g.png")
  bs_tkimage_create("::image::bs_restart_r",   "icons/16/refresh-rr.png")
  bs_tkimage_create("::image::bs_close_rcmdr", "icons/16/system-shutdown-6g.png")
  bs_tkimage_create("::image::bs_close_r",     "icons/16/system-shutdown-6r.png")

  bs_tkimage_create("::image::bs_workspace",   "icons/16/bs-documents-ws.png")
  bs_tkimage_create("::image::bs_open_wd",     "icons/16/bs_folder_open.png")
  bs_tkimage_create("::image::bs_path_to_wd",  "icons/16/bs_folder_show.png")
  bs_tkimage_create("::image::bs_print_wd",    "icons/16/bs_folder_print.png")
  bs_tkimage_create("::image::bs_set_wd",      "icons/16/bs_folder_change.png")
  bs_tkimage_create("::image::bs_folder",      "icons/16/bs_folder.png")

  bs_tkimage_create("::image::bs_help",        "icons/16/help-2.png")
  bs_tkimage_create("::image::bs_about",       "icons/16/help-about-3.png")
  bs_tkimage_create("::image::bs_ses_info_br", "icons/16/help-about-3-br.png")
  bs_tkimage_create("::image::bs_ses_info_g",  "icons/16/help-about-3-g.png")
  bs_tkimage_create("::image::bs_about",       "icons/16/help-about-3.png")
  bs_tkimage_create("::image::bs_bug",         "icons/16/bug.png")
  bs_tkimage_create("::image::bs_home",        "icons/16/go-home-6.png")
  bs_tkimage_create("::image::bs_question",    "icons/16/question.png")
  # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
}

# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.onAttach <- function(libname, pkgname) {
  if (!interactive()) {
    return()
  }

  # Options ------------------------------------------------------------------
  # Current options
  Rcmdr_opts <- getOption("Rcmdr")

  # If empty, convert to named list
  if (is.null(Rcmdr_opts)) {
    Rcmdr_opts <- list(plugins = NULL)
  }

  # Plugins to add
  recommended <- c("RcmdrPlugin.KMggplot2", "RcmdrPlugin.biostat")

  add_plugins <- recommended[recommended %in% .packages(all.available = TRUE)]

  # Add plugins in certain order
  plugins <- c(
    setdiff(Rcmdr_opts$plugins, add_plugins),
    rev(sort(add_plugins))
  )

  # Open 3-window Rcmdr, if options is not defined
  if (is.null(Rcmdr_opts$console.output)) {
    console.output <- FALSE

  } else {
    console.output <- Rcmdr_opts$console.output
  }

  # Use (un)sorted vector of variable names
  if (is.null(Rcmdr_opts$sort.names)) {
    sort.names <- FALSE

  } else {
    sort.names <- Rcmdr_opts$sort.names
  }

  # For Mac
  if (MacOSXP() && is.null(Rcmdr_opts$suppress.X11.warnings)) {
    suppress.X11.warnings <- TRUE

  } else {
    suppress.X11.warnings <- Rcmdr_opts$suppress.X11.warnings
  }

  updated_opts <-
    utils::modifyList(
      Rcmdr_opts,
      list(
        plugins = plugins,
        sort.names = sort.names,
        # fun_mod_commander = RcmdrPlugin.biostat::set_biostat_mode,
        console.output = console.output,
        suppress.X11.warnings = suppress.X11.warnings
      )
    )

  if (!identical(Rcmdr_opts, updated_opts)) {
    # Set new options and restart R Commander
    options(Rcmdr = updated_opts)

    cmd <- paste(capture.output(dput(updated_opts)), collapse = "")
    cmd <- sub("list(", "list(\n", cmd, fixed = TRUE)
    cmd <- gsub(", ", ",\n", cmd, fixed = TRUE)
    cmd <- paste0("options(Rcmdr = ", cmd, "\n)")

    packageStartupMessage(
      "\n\n==================================================================\n",
      "R Commander options were changed to: \n",
      "------------------------------------------------------------------\n",
      style_cmd(cmd),
      "\n------------------------------------------------------------------\n",
      "To take effect, the Commander should be RESTARTED.\n",
      "To get more information on R Commander options, run code:",
      "\n------------------------------------------------------------------\n",
      'help("Commander", package = "Rcmdr")',
      "\n==================================================================\n\n"
    )

    # if (is_commander_open()) {
    #   if (!isTRUE(Rcmdr::getRcmdr("autoRestart", fail = FALSE))) {
    #     restart_commander()
    #   }
    # }
  }
}

# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Create icons
bs_tkimage_create <- function(name, file, package = "RcmdrPlugin.biostat") {
  tcltk::tkimage.create(
    "photo", name,
    file = system.file("etc", file, package = package))
}


## A modified version of tcltk2::addTclPath()
add_tcl_path <- function(path = ".") {
  if (.Platform$OS.type == "windows") {
    path <- gsub("\\\\", "/", path)
  }
  paths <- as.character(tcltk::tcl("set", "::auto_path"))
  if (!path %in% paths) {
    tcltk::tcl("lappend", "::auto_path", path)
  }
}

# Add Tcl path of directory of installed R package
bs_add_tcl_path <- function(path, package = "RcmdrPlugin.biostat") {
  add_tcl_path(system.file(path, package = package))
}


# ============================================================================
state.tk2widget <- function(x, ...) {
  as.character(tkcget(x, "-state", ...))
}

print.tk2widget <- function(x, ...) {

  if (disabled(x)) txt <- " (disabled)" else txt <- ""
  cat("A tk2widget of class '", class(x)[1], "'", txt, "\n", sep = "")
  cat("State: ", paste(state(x), collapse = ", ", sep = " "), "\n", sep = "")
  cursize <- size(x)
  if (cursize > 0) {
    cat("Size: ", cursize, "\n", sep = "")
  }
  val <- value(x)
  if (!is.null(val)) {
    cat("Value:\n")
    print(value(x))
  }
  return(invisible(x))
}
# ============================================================================