R/utils-desc.R

In tidylab/tidylab.utils: The tidylab Utils Package

# load_packages_mentioned_in_description ---------------------------------------
#
#' @title Load the Project/Package Packages
#'
#' @description Loads the project's R packages defined in the DESCRIPTION file.
#'
#' @details GIVEN a \code{path} pointing at a directory containing a valid
#'   DESCRIPTION file, AND that file contains dependencies, THEN the function
#'   loads the defined packages.
#'
#' @param path (`character`) A path to the project's root folder.
#'
#' @return NULL. Prints information about how many packages were loaded and if
#'   applicable, which packages failed to load.
#'
#' @examples
#' \dontrun{
#' load_packages_mentioned_in_description(path = rprojroot::find_rstudio_root_file())
#' }
#'
#' @export
#' @keywords internal
#'
load_packages_mentioned_in_description <- function(path) {
    ###########################
    ## Defensive Programming ##
    ###########################
    stopifnot(dir.exists(path))
    target <- file.path(path, "DESCRIPTION")
    if(isFALSE(file.exists(target))) stop("There is no DESCRIPTION file in ", path)

    ###################################
    ## Get Packages from DESCRIPTION ##
    ###################################
    description_obj <- desc::description$new(file = path)
    description_obj$del_dep(package = "R")
    dependencies_table <- description_obj$get_deps()
    if(nrow(dependencies_table) == 0) return(invisible())
    dependencies_table$flag <- FALSE
    for(k in seq_len(nrow(dependencies_table)))
        suppressWarnings(
            suppressPackageStartupMessages(
                dependencies_table[k, "flag"] <-
                    require(
                        dependencies_table[k, "package"], quietly = TRUE,
                        warn.conflicts = FALSE, character.only = TRUE)
            )
        )


    ######################
    ## Show Information ##
    ######################
    n_failure <- sum(dependencies_table[, "flag"] == FALSE)
    n_success <- sum(dependencies_table[, "flag"] == TRUE)
    message("Preloaded ", n_success, " out of ", n_success + n_failure, " packages declared in DESCRIPTION.")
    if (n_failure >= 1){
        packages_names <- unlist(subset(dependencies_table, flag == FALSE, select = "package"))
        message(paste0(c("Couldn't load the following packages:", packages_names), collapse = "\n-> "))
    }


    ############
    ## Return ##
    ############
    return(invisible())
}