Defining custom preparations and checks

make_prep(name, func)

make_check(description, check, gp, ...)



Name of the preparation function.


A function that takes two arguments: The path to the root directory of the package, and a logical argument: quiet. If quiet is true, the preparation function may print out diagnostic messages. The output of this function will be saved as the " name" entry of state, i.e. of the input for the check-functions (see example).


A description of the check.


A function that takes the state as an argument.


A short description of what is good practice.


Further arguments. Most important: A preps argument that contains the names of all the preparation functions required for the check.


  • make_prep: Create a preparation function

  • make_check: Create a check function


# make a preparation function
url_prep <- make_prep(
  name = "desc", 
  func = function(path, quiet) desc::description$new(path)
# and the corresponding check function
url_chk <- make_check(
  description = "URL field in DESCRIPTION",
  tags = character(),
  preps = "desc",
  gp = "have a URL field in DESCRIPTION",
  check = function(state) state$desc$has_fields("URL")
# use together in gp():
# (note that you have to list the name of your custom check in
# the checks-argument as well....)
bad1 <- system.file("bad1", package = "goodpractice")
res <- gp(bad1, checks = c("url", "no_description_depends"),
          extra_preps = list("desc" = url_prep),
          extra_checks = list("url" = url_chk))
#> Preparing: desc
#> Preparing: description