Detect Default Paths in Exported Function Arguments

CRAN does not allow exported functions to default a path-like argument to a concrete location. This checker parses R source, finds exported functions, and reports every argument whose name matches arg_pattern and whose default value is not in allow (by default only NULL; an argument with no default is always fine). Each hit is reported with file, line, column and a caret (^^^^) marker under arg = default.

Usage

package_fn_arg_path(
  path = NULL,
  arg_pattern = "path|file|filename",
  allow = "NULL",
  dirs = "R",
  verbose = TRUE,
  ...
)

detect_fn_arg_path(
  path = NULL,
  arg_pattern = "path|file|filename",
  exports = NULL,
  export_patterns = character(),
  allow = "NULL",
  verbose = TRUE,
  ...
)

Arguments

path

For detect_fn_arg_path(): path to an R file. If NULL and RStudio is available, the active document is used.

For package_fn_arg_path(): root directory of an R package. Defaults to the current directory.

arg_pattern

Regular expression matched (unanchored) against argument names. Use e.g. "^(path|file|filename)$" to avoid matching profile.

allow

Character vector of default-value expressions (as written in the source, whitespace trimmed) that are acceptable. Defaults to "NULL".

dirs

Package-relative directories scanned by package_fn_arg_path().

verbose

Whether to emit results to the console.

...

Unused.

exports

Character vector of exported function names.

export_patterns

Character vector of regular expressions, as in exportPattern() in NAMESPACE.

Value

Invisibly returns TRUE if no offending defaults are found, FALSE otherwise.

Single file vs package scope

detect_fn_arg_path()

Operates on one R file. Use exports / export_patterns to say which top-level functions count as exported; when exports is NULL and no patterns are given, every top-level function in the file is checked.

package_fn_arg_path()

Checks that path is an R package, reads exports from NAMESPACE, then scans .R files under dirs (default "R").

Examples

# \donttest{
file <- tempfile(fileext = ".R")
writeLines('read_it <- function(path = "~/data.csv", n = 1) NULL', file)
detect_fn_arg_path(file)
#> /tmp/RtmpvrXwDA/file19ce1ac01bb9.R:1:21 read_it(): `path` defaults to
#> "~/data.csv"
#> read_it <- function(path = "~/data.csv", n = 1) NULL
#>                     ^^^^^^^^^^^^^^^^^^^
#> ✖ Found 1 argument with a default path in /tmp/RtmpvrXwDA/file19ce1ac01bb9.R
# }