Detect print() and cat() Calls (CRAN-Unsafe)

Check whether R source files contain direct calls to print() or cat(), which are generally not permitted by CRAN policies. Output should use message instead.

These functions parse R source code into an AST and identify every SYMBOL_FUNCTION_CALL token whose text is "print" or "cat". Each match is reported with the line number, the full source line, and a caret marker pointing at the offending call.

When fix = TRUE, the function performs a simple text replacement of print( and cat( with message( on the affected lines. The replacement uses word-boundary matching to avoid false positives inside other identifiers (e.g. sprintf or print.myclass).

Usage

package_print_and_cat(
  path = NULL,
  dirs = c("R", file.path("tests", "testthat")),
  test_included = lifecycle::deprecated(),
  fix = FALSE,
  ...
)

detect_print_and_cat(
  path = NULL,
  fix = FALSE,
  pattern_fn_names = DEFAULT_PATTERN_FN_NAMES,
  replace_default_pattern = FALSE,
  include_s3 = TRUE,
  include_refs = FALSE,
  verbose = TRUE,
  ...
)

Arguments

path

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

For package_print_and_cat(): path to the root directory of an R package. If NULL, the function walks up from the active document to find the package root.

dirs

Character vector of package-relative directories scanned by package_print_and_cat(). Defaults to "R" and "tests/testthat".

test_included

. Logical indicating whether to scan tests/testthat/ in addition to R/. Use dirs instead. When supplied, FALSE scans only R/; TRUE scans both default directories.

fix

Logical. If TRUE, replace print(/cat( with message( directly in the source file(s). Default is FALSE.

...

Additional arguments passed to utils::methods (currently unused).

pattern_fn_names

Character vector of regular expressions matching function names whose return value is treated as a diagnostic string. A print() whose first argument is a string literal or calls a matching function is flagged as a message. Extra patterns are appended to the default set unless replace_default_pattern = TRUE.

To obtain the default patterns, use rpkgkit:::DEFAULT_PATTERN_FN_NAMES.

replace_default_pattern

Logical. If TRUE, pattern_fn_names fully replaces the default set instead of extending it.

include_s3

Logical. If TRUE, report print() calls whose first argument is not string-like (S3 object printing). Default TRUE.

include_refs

Logical. If TRUE, also report bare print/cat symbols (e.g. lapply(x, print)). Default FALSE.

verbose

Whether to output information in console

Value

Invisibly returns TRUE if no calls were found, FALSE otherwise. Side-effect messages and caret markers are emitted via cli and message.

Single file vs package scope

detect_print_and_cat()

Operates on one R file. When path is NULL and RStudio is available, the currently active document is used automatically.

package_print_and_cat()

Scans all .R files in a package's R/ directory, plus tests/testthat/ when test_included = TRUE. Results are aggregated into a single report showing per-file summaries.

Examples

# \donttest{
# --- Single file ---
tmp <- tempfile(fileext = ".R")
writeLines('print("hello")', tmp)
detect_print_and_cat(tmp)
#> print("hello") [message]
#> ^^^^^^
#> ✖ Found 1 unsupported call on line 1.

# --- With auto-fix ---
detect_print_and_cat(tmp, fix = TRUE)
#> ✔ Fixed 1 line in file19a42d4cef9a.R.
#> print("hello") [message]
#> ^^^^^^
#> ✖ Found 1 unsupported call on line 1.

# --- Entire package ---
pkg <- tempfile()
dir.create(file.path(pkg, "R"), recursive = TRUE)
writeLines('cat("debug\\n")', file.path(pkg, "R", "example.R"))
writeLines(c("Package: example", "Version: 0.0.1"),
           file.path(pkg, "DESCRIPTION"))
package_print_and_cat(pkg)
#> R/example.R: 1:
#> cat("debug\n") [message]
#> ^^^^
#> ✖ Found `print()`/`cat()` calls in 1 of 1 file.
# }