R/load.R

In heavywatal/namaespace: Utility to create dummy R packages for namespace

#' Extract export lines from NAMESPACE
#' @param package A string
#' @return A string vector of \code{export()} lines in NAMESPACE
#' @rdname load
#' @export
#' @examples
#' exported_from('readr')
exported_from = function(package) {
  stopifnot(!package %in% c("base"))
  infile = system.file("NAMESPACE", package = package)
  content = readChar(infile, file.info(infile)$size)
  content = gsub("#.+?(\\n|$)", "", content)
  pattern = "export\\([[:graph:][:space:]]+?\\)"
  stringr::str_extract_all(content, pattern)[[1L]]
}

#' Load packages and put all objects into a namespace
#' @param namespace A string
#' @param packages A string vector
#' @rdname load
#' @export
#' @examples
#' \dontrun{
#' load_in_namespace('tdy', c('ggplot2', 'tibble', 'tidyr', 'readr', 'purrr', 'dplyr'))
#' }
load_in_namespace = function(namespace, packages) {
  installed = rownames(utils::installed.packages())
  stopifnot(all(packages %in% installed))
  path = file.path(tempdir(), namespace)
  unlink(path, recursive = TRUE)
  title = sprintf('Dummy package to use a namespace "%s".', namespace)
  description = list(
    Package = namespace, Title = title,
    `Authors@R` = getOption("devtools.desc.author"),
    Description = title,
    License = "MIT",
    Imports = paste(packages, collapse = ", "),
    URL = "https://github.com/heavywatal/namaespace",
    BugReports = "https://github.com/heavywatal/namaespace/issues"
  )
  devtools::create(path, description = description, rstudio = FALSE)
  imports = sprintf("import(%s)", packages)
  exports = unlist(lapply(packages, exported_from))
  output = paste(c(imports, exports), collapse = "\n")
  cat(output, file = file.path(path, "NAMESPACE"))
  devtools::load_all(path)
}