Setup use of a new, fresh library directory in R

fresh_r_libraries.r

create_lib_dir <- function(name, path = "."){
  
  dir_path <- file.path(path, name)
  if (!dir.exists(dir_path)) {
    message("Creating new dir: ", dir_path)
    dir.create(dir_path)
  }
  
  normalizePath(dir_path)
}

use_local_library <- function(dirname = "libs", dirpath = "."){
  
  full_dir_path <- create_lib_dir(dirname, dirpath)
  
  if (!file.exists(".Renviron")){
    message("Creating .Renviron file")
    file.create(".Renviron")
  } 
  
  new_line <- paste0("R_LIBS_USER = \"",full_dir_path, "\"")
  
  current_lines <- readLines(".Renviron")
  
  if (!(new_line %in% current_lines)){
    message("Adding line to .Renviron: ", new_line)
    con <- file(".Renviron", encoding = "utf-8")
    on.exit(close(con), add = TRUE)
    cat(new_line, file = con, sep = "")
  }
  
  message("Restart R to take into effect.")
  invisible(TRUE)
}