R/rename.R

In mikmart/rmdmatter: Make the Most of R Markdown YAML Front Matter

#' Rename a rendered file with YAML front matter metadata
#'
#' @param file A string that gives the path to the file to rename. Should be the
#'   result of [render()] in order to have metadata attached.
#' @param callback A function that gets the rendered R Markdown YAML front
#'   matter metadata as an argument, and returns a new name for `file`. Any
#'   changes implied to the directory or file extension are ignored -- only the
#'   name is changed.
#'
#' @return A string that gives the path to the renamed file.
#' @seealso [render()] for creating an object to use as the `file` argument.
#'
#' @examples
#' \dontrun{
#' # Make sure to use rmdmatter's render() to have metadata available
#' output_file <- rmdmatter::render(input_file)
#' rename_rendered(output_file, function(metadata) {
#'   with(metadata, paste(title, "by", author, "on", date))
#' })
#'}
#' @export
rename_rendered <- function(file, callback) {
  metadata <- rmd_metadata(file)

  # Allowing directory changes would cause confusion if `file` is not in the
  # current working directory -- would the result be relative to the current
  # directory or to the original file? Relative to current directory seems
  # like the "correct" but less useful behaviour. Simpler to disallow it.
  #
  # Explicitly specified file extensions could be allowed, and still inherit
  # the extension if not specified. I don't really see a use for that though,
  # so we avoid a branch by leaving it out unless a real need somehow arises.
  new_name <- fs::path_file(callback(metadata))
  new_file <- fs::path_ext_set(new_name, fs::path_ext(file))
  new_path <- fs::path(fs::path_dir(file), new_file)

  fs::file_move(file, new_path)
}