R/zzz.R

In rudeboybert/fivethirtyeight: Data and Code Behind the Stories and Interactives at 'FiveThirtyEight'

.pkgenv <- new.env(parent = emptyenv())

.onLoad <- function(libname, pkgname) {
  has_data <- requireNamespace("fivethirtyeightdata", quietly = TRUE)
  .pkgenv[["has_data"]] <- has_data
}

.onAttach <- function(libname, pkgname) {
  if (!.pkgenv$has_data) {
    msg <- paste(
      "Some larger datasets need to be installed separately,",
      "like senators and house_district_forecast.",
      "To install these, we recommend you install the ",
      "fivethirtyeightdata package by running: ",
      "install.packages('fivethirtyeightdata', ",
      "repos = 'https://fivethirtyeightdata.github.io/drat/', type = 'source')"
    )
    msg <- paste(strwrap(msg), collapse = "\n")
    packageStartupMessage(msg)
  }
}

hasData <- function(has_data = .pkgenv$has_data) {
  if (!has_data) {
    msg <- paste(
      "To use this function, you must have the",
      "`fivethirtyeightdata` package installed. See the",
      "`fivethirtyeightdata` package vignette for more details."
    )
    msg <- paste(strwrap(msg), collapse = "\n")
    stop(msg)
  }
}